Noob question, Princes of the Apocalypse

A friend of mine is starting a Descent into Avernus campaign. We're all new to Roll20 and are still in the process of purchasing the add ons. I want to gift him with Princes of Apocalypse for the races and spells that the ToEE Players Companion contained. I just want to make sure that those features will be available in our Descent campaign. Appreciate any help you all can give me.

PotA was built before the Charactermancer existed. So, the information from the Player's Companion is included, but not as Compendium integration; rather, it is on handouts within the journal. So, it won't provide the integration you are currently looking for. The devs have mentioned going back and eventually fixing up old modules to include newer features like this, but it hasn't happened yet. If you want to use options from the Player's Companion, you'll have to do them as manual custom items.