As an admin, you can purchase and install add-ons apps from the Atlassian Marketplace inside your application. In some organizations, the person who approves purchasing software might not be the same person with admin privileges in the UPM. In this case, the purchaser might buy the add-on app from the Marketplace directly, instead of within the admin console.
To use the features on the Purchased add-ons page, UPM must be connected to the Marketplace and the Atlassian application instance must have a valid Support Entitlement Number (SEN).