Adding Xanathar's content to Lost Mines (new to Roll20)

We are about to start a Lost Mines D&D campaign but most of the players want to use content from Xanathar's or other official DnD material. I wanted to ask if I purchased Xanathar's and the other content from the marketplace, does all the content (i.e. spells, subclasses, etc.): Becomes instantly available in the existing campaign OR Do we have to start a new campaign None of the above Thanks.

Option 1. Xanathar's Guide is primarily a Compendium. As such, it behaves as the Player's Handbook. All spells, classes and races are available in any game the owner of the compendium has created, and are available to players in that game according to the Compendium Sharing Rules : Free Users  Free users may purchase any compendium. They may only share their purchased compendiums with one active game that contains no more than themselves plus 5 players (6 total). Plus Subscribers  Roll20 Plus subscribers may purchase any compendium. They may share their purchased compendiums with three active games that contain no more than themselves plus 10 players each (11 total per game). Pro Subscribers  Roll20 Pro subscribers may purchase any compendium. They may share their purchased compendiums with five active games that contain no more than themselves plus 15 players each (16 total per game).

Keith is correct, but I did want to add that there are a couple of other items that come with Xanathar's that are accessed slightly differently than the compendium content. The first is the Underworld Speculation adventure. This is a module, and the way to access it is by creating a new game and choosing it as the base module. As such you can't easily add this adventure to your LMoP game without the Pro feature of the Transmogrifier, which you can use to copy everything from one game to another. Second is the Bonus Character Asset Pack, which is art from the book. This should appear in your Art Library in every game you run under Marketplace Purchases -> Xanathar's Guide to Everything (Character Asset Pack). Regarding the other books (Volo's and Mordenkainen), the Roll20 team is working to get those integrated into the Charactermancer, but they do not have support there yet. I would expect it shortly, but there hasn't been an exact time-frame given. The content will appear in your Compendium, it just isn't all drag and drop/Charactermancer enabled yet.