This may be a dumb question, but does one have to be affiliated with a publisher or game designer to host an event using their platform? I noticed that all the Tal'dorei related events last year were hosted by Green Ronin Publishing, the company that published the campaign setting book. I was planning on submitting a couple of events in the same setting, but wanted to make sure it was OK, since I'm just a random dude not affiliated with the Critical Role people in any way.
You don't have to be Green Ronin Freebooter to run a Tal'dorei at Gen Con or any other convention. That being said there are some perks with being a Freebooter
If you are curious here is the info about being a Freebooter https://greenronin.com/freebooter/
You do not need to be officially associated with or managed by any company or publisher to run events at Gen Con, though there are some details that can matter, depending on the type of game and event you want to run (officially sanctioned tournaments, for example, require coordination, but general games usually don't).
For RPGs in specific, you are welcome to just run a game. You don't need to do it through Green Ronin, though you may want to check with them because some companies do indeed offer perks for doing so.
Senior Event & Program Manager
Gen Con LLC