@chairbfroblox,
You will need to have a need for a forum. It can’t just be a single-person project to be eligible for free hosting. As Simon said, anything related to Roblox will not be eligible for the free forum. In terms of something eligible, our forum initially was one of the free-hosters until we upgraded to Business Plan at a discount price. Here’s an open-source project that’s eligible(This is ours):
https://github.com/codecombat/codecombat/
Thanks to Discourse, our forum is running with the best support available. Originally they had a higher-criteria, but they recently lowered it, but you’ll still need to have a good reason for a free-hosting. (1000 star requirement to none).
Additionally, Discourse’s source code is 100% free(GitHub - discourse/discourse: A platform for community discussion. Free, open, simple. · GitHub), so if you want to, you can self-host it with 0 fees. Additionally if you just need a sandbox forum to try things out, you can always setup a developer environment and test some features there.