The migration of multiple WordPress websites utilizes exactly the same process as single WP site migration.
The only difference is that there are multiple websites, which means multiple files and multiple databases need to be migrated.
In other words, migration of multiple WP sites is the same as a single WP site migration, just done multiple times.
This also means that required logins are the same:
- WP-admin(dashboard) username and password
- Current hosting login(cPanel or equivalent)
- New hosting login(cPanel or equivalent)