The ADA statute identifies who is a person with a disability, who has obligations under the ADA, general non-discrimination requirements and other basic obligations. It delegates fleshing out those obligations to federal agencies. The agencies issue regulations and design standards. The regulations have the details on the rights of people with disabilities and responsibilities of employers, state and local governments, transportation providers, businesses and non-profit organizations. The design standards specify how many entrances need to be accessible, how many toilet rooms and the design for those elements.  To know what the ADA requires, you need to read the law, regulations and design standards.  

The 2014 case involving Peapod, an online grocery retailer emphasizes that being ADA compliant goes beyond your website. The settlement required Peapod to make its mobile applications accessible by March 2015 and its website accessible by September 2015. Since mobile apps are fast becoming the preferred method of online shopping, e-commerce sites must focus on app accessibility too. 

This guidance document is not intended to be a final agency action, has no legally binding effect, and may be rescinded or modified in the Department's complete discretion, in accordance with applicable laws. The Department's guidance documents, including this guidance, do not establish legally enforceable responsibilities beyond what is required by the terms of the applicable statutes, regulations, or binding judicial precedent.

A person’s method(s) of communication are also key. For example, sign language interpreters are effective only for people who use sign language. Other methods of communication, such as those described above, are needed for people who may have lost their hearing later in life and do not use sign language. Similarly, Braille is effective only for people who read Braille. Other methods are needed for people with vision disabilities who do not read Braille, such as providing accessible electronic text documents, forms, etc., that can be accessed by the person’s screen reader program.
As I mentioned above, under each WCAG 2.1 principle is a list of guidelines, and under each guideline are compliance standards, with techniques and failure examples at each level. Some guidelines include only Level A items; others include items for multiple levels of conformance, building from A to AAA. At each stage, you can easily see what more you would need to do to reach Level AA or AAA. In this way, many websites include elements at multiple levels of accessibility.
Again using the WAVE toolbar, check for Errors, Features, and Alerts. If there are many errors, I assume this page will not serve as a good example, and stop checking. If there are only a few errors (e.g., fewer than five) I'll check those errors and might be forgiving if they're relatively minor and are offset by good accessibility in other areas.
The ADA requires that title II entities (State and local governments) and title III entities (businesses and nonprofit organizations that serve the public) communicate effectively with people who have communication disabilities. The goal is to ensure that communication with people with these disabilities is equally effective as communication with people without disabilities.
You probably won't have to check your site with all of the available evaluation tools out there, but it is a good idea to do so for the most common web browsers. Just as accessibility software makes it easier for people with disabilities to navigate the Internet, these tools make it easier for developers to ensure accessibility from the start. When you think you've mastered it, go back through the Section 508 compliance checklist to ensure you've met every goal.
Accessibility by UserWay UserWay creates a simpler and more accessible browsing experience for users with mobility issues. Millions of people cannot use a mouse or other pointing device and rely solely on their keyboard to navigate websites. Your site should be fully navigable using a keyboard’s tab key, arrow keys, the enter key and the space bar.

My request at this point is if the developers of the plugin could please implement a solution like this so that the plugin can be compliant natively, without me having to jump in and edit the code every time the plugin is updated. It doesn’t need to be this solution exactly, as this is admittedly a bit of a rough fix, but if the buttons could be modified with ADA compliance in mind, it would make things a lot easier for sites that use this and have these requirements to meet.

Although the plugin works, we activated the white label solution. They said: For only $10 you can modify the widget footer, remove the donate link and enable other customizations From then and on they charge me every single month 10$, they don't reply to my messages and the so called "Manage" menu has been disappeared from the widget... BE AWARE! I'm still trying to resolve this....
Reha asked Vu if companies are obligated to comply? Vu said that unlike the physical access world, where any new building has to be compliant no matter what, there’s no such thing in the web world. The Justice Dept. hasn’t said that that’s the default, but they have said that the current regulatory regime requires it anyway. Equal access has been around since 1990.