For the backups that exist only on the Datto cloud, there's a different way to do Files Restores and Cloud Virtualization through the partners portal with a different login that we will create for you. Once the account is created you'll receive an automatic email to create a password. Then, to perform restores, you have to click on the menu Devices > Recovery Launchpad, and follow the instructions from the document attached.
To create new users, it has to be done, see attached the document Manage Clients on Datto Portal.