How to get user-generated content for your app/website.

I am creating a website where users can review and rate content creator's paid content. Think of it as a yelp for patreon, onlyfans, etc. However, in order for this website to gain traction, there must be enough users providing reviews.

So i am wondering, how do people here get users to generate content for their apps/websites?

I tried to post to some subreddits related to this topic, but i feel like most subreddits have rules against this stuff. (I actually dm'd a mod directly to see if I can post and ask for reviews and they just proactively banned me from the sub)

Did you decide who is your main audience? I think acquisition channels strongly correlate with image of your ideal consumer. Secondly, I suggest you to think what is the main push factor for people to perform reviews and set rates on your platform. Depends on it you can find active slices of audience.
P.S. Pls share your experience when you'll solve your problem :)

That is hard to say. Users need to feel like they are getting a benefit in order to want to comment/ add reviews themselves.