The old Flexera SaaS Manager (FSM) can pickup ex SSO Application Discovery (ex EntraID), so if you are using that SSO technology you can atleast catch the users and login activity. It also exists a Ingestion tool where you can use API or CSV imports to be uploaded to SaaS Manager.

The new FLexeraONE SaaS Manager (FOSM) have also the possibility with EntraID SSO discovery and there are also a CSV import functionality to import users and activity. We usually ask AI (Copilot/ChatGPT) to develop those kind of scripts in regardless if its onprem or cloud/saas and then you need to import it for the first time and then FOSM will expose an API to programatically update the data which you then also can ask AI to develop the script. If the application doesnt exists then you can define it in the Private SaaS Catalogue

Function resides under Administration->FlexeraONE SaaS Manager Settings->DataImport

Flexera is also on its way to release an eLearning for how to work with data imports I saw in another thread.