Because the ADA establishes overlapping responsibilities in both EEOC and DOJ for employment by State and local governments, the Federal enforcement effort is coordinated by EEOC and DOJ to avoid duplication in investigative and enforcement activities. In addition, since some private and governmental employers are already covered by nondiscrimination and affirmative action requirements under the Rehabilitation Act of 1973, EEOC, DOJ, and the Department of Labor similarly coordinate the enforcement effort under the ADA and the Rehabilitation Act.
Aloha Tatiana! I wish your questions had straightforward easy answers – and if you are government funded it kind of is. (See here: https://www.ada.gov/websites2_prnt.pdf) if you are not government funded, this is something that is currently being debated in the legal system. That being said, the WCAG 2.0 guidelines are a good set of guidelines to help protect yourself if you feel you should. (You can see more on WCAG here: https://www.yokoco.com/find-out-how-to-make-your-website-compliant/)
Until the ADA is updated to address the special case of website accessibility, or the Department of Justice releases its website accessibility regulations, complying with WCAG 2.0 Level AA is the best way to ensure that people with disabilities have equal access to your website. The overview below is a great starting point about meeting the WCAG 2.0 Level AA recommendations.