I would venture a guess at no, it looks like wix uses its own site templates (like you select from their stuff and pick one) and it seems the whole point of that site is to let people make tiny simple pages without actually learning anything that they can take somewhere else, and I don't even know if you can have a database on their system which is needed for just about any forum.
You need a real server that you can call your own, even if it is a cheap shared environment.
Wix does not support things like PHP and MySQL DBs. To use XF, you would need separate hosting for the forum part of the web site (though that may be slightly difficult to incorporate with Wix itself).
It's entirely up to you which host you go with, as long as they comply with the requirements.
Typically it depends on your budget, whether you want shared or VPS, managed or unmanaged, cPanel (or similar) or none.
Installation is relatively easy if you know how to FTP files and create a database instance.