I just Google “Disney world convention March 2024” (or whatever date) and poke around convention websites until I find one with a ticket link. I’ve never had an issue using them without being associated with the convention. Also, they aren’t date based which is nice (typically they expire at the end of the year in which the convention is being held, but that can vary), but because they aren’t date based, that does mean you still need to make park reservations with them (just like with an AP).