Clarification - Modules and Existing Games

I've been running a D&D game for the past several months on Roll20.  Someone online suggested I might enjoy using one of the premade modules in the Roll20 Marketplace. My understanding is that, if I purchased that, I would have to then start a new  game in Roll20, and have my Players use that  game instead of our existing game. Is that correct? So I would have to recreate or (if possible) export/import all of the Handouts and tokens and such that I've already created for my existing game?   This seems....well, it seems like a big hassle.  Is this really  how it's got to be done? If you want to use the same characters and handouts and other creations, you've got to actually go from game to game instead of just importing new assets into one singular game? I'm befuddled.

For modules, yes, you can only create them in a new game.  Addons can be added to an existing game.  Some modules aren't as large as others of course, but things are this way partly to save Roll20 users (and the servers) from themselves.  You can get a large enough game to cause game lag, cause the server to time out during game copy operations, etc.  So they don't make it easy to get your game large enough to cause problems. That said, if you upgrade your account to pro, you gain access to the transmogrifier, which allows you to pretty freely move anything except macros from one game to another.  You could just do pro for a month, build your frankencampaign, and then drop back down to plus.

Yeah, that's how it is with campaign-sized material that are modules . Some smaller adventures are addons, which can be added to existing games. Pro users can use the Transmogrifier to move more than just characters between campaigns.

Very enlightening! Thanks so much, folks!