When using Workspace 365 please keep the following best practices in mind:
Do not change the domain name of an Office365 user that already exist in your Workspace365 environment.
If you wish to change the login domain of your Office365 accounts, change this before creating your Workspace365 environment.
When possible do not change the password of the primary admin account through Office365.
Workspace365 uses the primary admin account for a number of functions, if the password does not match services within your Workspace365 environment might not work.
It is also possible to create a second administrator account. This method is preffered. The primary administrator account does not need a Office365 license after you are done with the initial configuration. Please check Preparing for a secondary admin account FAQ article for a how-to.
In both cases we urge you to keep track of the password expiry policy of your administrator user. If preferred you can disable the policy on your administrator account. To do so, follow the following link.
For the best usage of the Workspace365 Documents functionality make sure each user has opened OneDrive Within office365 at least once.
For more info check Personal documents not visible in Workspace365 FAQ article