I'm late but still... FF here are mostly about Kpop. There are some other Asians FF tho. There are no ban for posting original fic but I should remind you that people come to this site to see FF, so they would be more attracted to FF.
Other Asian fanfics are welcome too although rare. Original fiction, though? I have a strong doubt you’ll find AFF very pleasing in terms of viewership as majority are here to read fanfiction. Then again, nobody bans you for writing an original fic here.
honestly-- it's ASIANfanfics, so I would say that fanfiction for anything Asian-related (mostly kpop fanfics on this site) would be acceptable, but if you're posting original fiction-- it's not really fanfiction, if you get what I mean?
I would post original fics on Wattpad imo. :))