Fundamentally, all purchased marketplace content is available to you in a game you create. Additionally, Compendiums can be made available to the players in your game (and selectively by each individual compendium). Using content you have purchased in a game you didn't create is generally limited to importing characters that you've created in one of your created games into someone else's created game. A few examples: I create a character in my game and assign it a portrait from a set I've purchased, and create and assign it a token from another set. I think export it to my Character Vault and then import it into someone else's Game using the Character Vault. I now have access to my marketplace content in someone else's created game. I create a spell template in my game and size it for the spell. I then create a character with the name of the spell. I set in player journals to all players and controlled by to all players, then update the token to represent it. I assign the token as the default token, then move it through the Character Vault to another player's game. That spell character is now accessible to any player to drag out and represent that spell. I create a game based on a marketplace module I've purchased. I then invite a friend to the game and promote them to GM. When I join the game, I switch to a player and they run my purchased module so I can play in it. Note that the Character Vault import must be enabled in the created Game, and is only available in Plus and Pro created games, and some games based on official marketplace content.
