It wont let me add my own custom content

[Mindyvolt]

Could someone help i wanna add my own custom content but idk how to open monogame and volcanic wont let me add them

 

[Raeven]

If you are talking about adding them to the buymode, then you need to edit the catalog_downloads.xml that they provided.
MarshmellowBear kindly posted a list of category numbers in the forum somewhere.