Thanks for the link. It says: "The ADA’s nondiscrimination mandate states that no qualified individual with a disability shall, by reason of such disability, be excluded from participation in or be denied the benefits of services, programs, or activities of a public entity, or be subjected to discrimination by a public entity." So, it's based on "services", not a place of public accommodation, and it (the letter) applies to public entities only.
There's another question that this situation raises: is a website a "place", a "service", or a "product"?
If it's a place, then place-of-public-accommodation rules might apply.
If it's a service, then it's likely to be treated like other services. For example, the ADA says that a barbershop must be accessible, but it doesn't say that the barber must cut the hair of a disabled person. (That would come under anti-discrimination statutes, not the ADA. I think. Not sure about this).
If it's a product, then there are probably no rules at all. There's no law that say that your faucet must be accessible to a person who can't turn small knobs, or that your book must have large-enough type to be read by the elderly.
Again, as I say, sorting all this out is going to be harder than you think.