My question is, why am I forced to "grant access" to macOS, when I DO NOT HAVE a Mac computer?
"By agreeing, you'll allow iOS and macOS to access...AOL Contacts; AOL Calendar; Profiles, AOL Mail."
iOS is used on iPhones and iPads. macOS is used on Mac computers. If you agree, you are allowing an iPhone, iPad, or Mac computer to access AOL data. If you don't have a Mac computer, then logic would dictate that this would not apply to you, correct? However, if you buy a Mac computer in the future, this will apply to you.
If you do not want to do this, then you will not be able to use AOL email.
Apple is not forcing you to do anything. If you don't want to use AOL Mail then don't "agree".
If you were using Yahoo, Hotmail, Gmail, or any other mail service, you would see the same notice for each service. You would not be able to use mail on any of the other services if you don't want to agree.