Hi there! Looks like you linked to a Lemmy community using a URL instead of its name, which doesn't work well for people on different instances. Try fixing it like this: !amarequests@lemmy.world
A rather infamous Reddit employee/administrator who's generally regarded as being responsible for the Golden aga of IAMA on Reddit (as she personally vetted and brought in some big name AMAs).
She was let go, which was one of the first instances of Reddit's foray into the realm of anti-community bullshit.
What is your plan for promoting the AMAs (on Lemmy or elsewhere), and collecting questions ahead of time? I think both of these would be an important kickstart for the AMAs, and help ensure their success. For example, a few posts like "Notable celebrity John Smith will be answering questions on August 1st from 11:00 to 13:00 UTC, post your questions for him here" in the weeks/days leading up to the AMA might be a good idea.
Thanks again for taking on this project; looking forward to seeing what comes of it!