Like Prodigy and Compuserve and GEnie and some others, it was an on-line information system. Chat, message boards, news, stock quotes, (limited) shopping, games, software downloads, etc. But all within a single system. Kind of like a nationwide/global BBS, but with a GUI interface. In the 80s, all these systems were independent, in the early 90s they got internet email, and the mid 90s added web browsers and (eventually) real tcp/ip.
All that said, I still communicate with one person who maintains their aol.com email address to this day in spite of it all.
Didn't they try to come back as a brand when free ad-supported dialups became a thing for a bit?
Related, while doing a quick search to see if I could learn anything about what you described I found Wikipedia quoting NYT as writing about EarthLink in 2000: "second largest Internet service provider after America Online". I guess it was around y2k when aol finally got its ISP (and this its "world's largest") designation by the world at large. :)
Wildcat was like aol for bbs but it immediately brought users to a web browser so they could get internet connectivity while still getting a pop up of the BBs’ services.
What you are missing is that “full isp’s” did not exist until about 1996, 1997. And even then AOL and secondarily Compuserve where the go to providers. Wildcat absolutely challenged that status quo in an independent manner