Have you deployed UIM Robot on customer's server ?
If yes, you can set tenant identifier using ORIGIN which is part of controller probe configuration.
controller IM Configuration - CA Unified Infrastructure Management Probes - CA Technologies Documentation
After ORIGIN is set properly, then you need to create ACCOUNT (Tenant identifier).
Grant ownership of appropriate ORIGIN in the account.
Create Account User within the account.
Above 3 work is done through Account Admin.
When the account user log In to UMP, it has data visibility for only devices which has ORIGIN granted in the account.
That is how Data Partitioning works out in CA UIM.
Regards,
Yu Ishitani