For SWL-Server, the "td" user only has "public" role and is the user that does the transactions for the end users in their projects.
The "Td_admin" (or whatever name you choose) user is a higher-level user that can create/delete and maintain projects.
Please have the DBA's assign no more no less than what is in the rights requirements.

https://admhelp.microfocus.com/alm/en/15.0-15.0.1/pdfs/Install_Windows.pdf

Look in section about MS SQL Database Prerequsites on page 52.  It says:

The td_db_admin login must have the Database Creators role. You must also grant the td_db_
admin login the Security Administrators role. This allows the td_db_admin login to create and add
the td user with only those privileges required for running ALM, and to run the Maintain Project
activities, such as Verify, Repair, and Update.

Additionally, you will need "System Administrators" role when upgrading ALM/QC projects.