To set up your azure service account for Azure backup, you need to allow access to your subscriptions that you want to backup.

Go to the desired subscription
Go to IAM in the subscrption
Create a new custom role
Go straight to JSON and click Edit
If provided by AnyCloud paste the permissions JSON data here, this will also set the name for the role.  Name will in this case be: Veeam Service Account (ID), you can go back to Basic, and change the name, or simply Add AnyCloud for identication purposes.
Click review and create, then create.
Create a new security group, give it a name that you can identify.  Add the member, which will be the App registration/Enterprise application created by the appliance or manually.
Once the group and application has been linked, we not need to link the role to the group.
Select role, and add member. in this part the member will be the group we've just created.
Once done, tell AnyCloud.  We will run a check to see if we have been granted permissions to the subscriptions.

Possible obstructions: Conditional access, MFA