The official way to run Discourse is with Docker and their own installer script. And to do that, you’ll need your own (virtual) server to run it. Discourse itself does not support any web hosting service.
Perhaps it’s possible to make it work on premium hosting, but expect it to be EXTREMELY painful to setup and maintain, and to not be possible at all.
Oh, and you don’t just need Ruby support, you also need a PostgreSQL database (which premium hosting has) and a Redis instance (which premium hosting does NOT have).
Discourse is a beast to run (speaking from experience). Don’t be stupid, add additional difficulty for yourself and just get a VPS for it and use the recommended installation method.