To create a linkage to a driver without a mobile phone number you have to go in the habblPortal to Administration and send a request to a diver. 

The following screenshots should show you the individual steps.

1. Click on the icon Administration
2. In the navigation area click Linkages
3. Click on SEND REQUEST  in the search area

        4. In the new window choose in the dropdown menu User identification (app user)
        5. In the second line enter your UNIQUE ID