What @WriterLinXiaolong said in regards to Eastern fantasy. It's basically stories that are modeled after the genres and themes that are popular in Eastern countries like China, Korea or Japan. If you haven't really read anything like that, maybe you can think of some movies instead. e.g. martial arts movies should still be pretty well-known in the west?
As for the TOS: Nope, you don't have to follow that of novelupdates. They're not really mirrored either. Novelupdates is basically a database for translations of Eastern novels to English. The translations aren't posted on novelupdates itself either but on other sites that are then linked on novelupdates. This is the site:
https://www.novelupdates.com/
You can just have a look at any random novel that was updated today if you want to see how it works But in general, they list some statistics and data about the novels (like author, number of chapters, original publisher, whether the translation is licensed or not) and then they have a list of the chapters and where people can find it.
ScribbleHub is working very much like novelupdates in terms of how it works with the search system, the reading lists etc but people post their stuff directly on ScribbleHub (so it's not just a database).
There are also some more western-like stories I'd say (so you're not forced to post Eastern stories) but most of the authors on there and the readers come from novelupdates and like eastern stories so that is currently the majority. It doesn't mean there isn't a market for anything else though. With the site growing bigger, there will likely spring up some more variety anyway.
Something that might be interesting for writers on Tapas: There are lots of people that love anything BL and/or yaoi on there as well (and lots of haters but that's another story ...). Eastern stories (actually, I'm mostly speaking about Chinese ones here, I don't really like Japanese and Korean stories all that much) also often run in arcs with bl novels sometimes incorporating more western arcs. Like I've seen European-looking vampires in one recently? And there are mermaids and sci-fi and stuff as well. So honestly, people are pretty open-minded. Everything just looks (and often sounds) a bit more Chinese.