If you're wondering if AOL still exists as a separate entity, the answer is no. AOL as a standalone ISP is no more.
What was AOL is now part of Verizon Media Group, which for a time was called Oath.
AOL, Yahoo and Verizon are all one mailbox provider, from a sender's perspective. The Yahoo CFL (Complaint Feedback Loop) aka FBL covers all of the legacy ISP domains that made up these separate providers. That includes aol.com, yahoo.com, verizon.net, and various other domains. You can find my best guess at a list of all Verizon Media (Oath) domains here.
If you're having problems delivering mail to AOL, you should look for guidance on how to resolve delivery problems to Yahoo Mail. Yahoo Mail's infrastructure is now hosting mail for all of the Verizon Media domains. If you have issues sending to aol.com, then you are also having problems delivering to yahoo.com, and the Yahoo Mail filters apply.
The Verizon/AOL/Yahoo Postmaster (sender information) website can be found here.