When you have set it up correctly, it'll work in the following way:
The first time a user tries to login to a Digizuite product using his or her AAD credentials, a new user will be created in your DAM with the email as its username. The new user's rights levels will be a copy of your chosen template user's rights levels, however, a change to the template user will not impact the user's rights after its creation. In order to have the template user and the users created by it to be in sync at all times, you need to make them use the same groups for maintaining rights.
Alternatively, you may create the user up front with the rights you choose. Be aware that the premade user's username must correspond 100% to the AAD user's. If this is not the case, a new user will be created with the template user's template instead (As previously mentioned)
How to invite an Azure user to use the application
In the Azure Active Directory section of the Portal, select "Enterprise applications"→"All applications" and select your application from the list. Then select "Users and groups" and click "Add". Click "Users (none selected)" and press the "Invite" button.