It is the owner of the account (or reseller) who needs to create a subscription. You can see who owns the account under Company/Company details.
Read about how a Univisor gives a customer access to a bookkeeping account and starts a subscription here.
Stand in the company you want to form a subscription with.
Go to Company/Maintenance/Subscription
Enter relevant information and press the 'Save subscription' button in the pop-up menu.
Read more about the fields here.
Read about Azure AD here.
A subscription has now been created for the user who owns this account.

