To add a license plate to a user, or to edit the existing license plate of a user you can follow these steps.
Go to Employees → Users and search for the user for whom you want to add or edit the license plate.
Right-click on the user and click List vehicles.
In the next screen, you can see the vehicle(s) that are already linked to this user. (In this example you can see that there are no vehicles linked to this user yet). To link a new vehicle, click on Add vehicle at the top right.
A pop-up screen will appear in which you can enter information about the vehicle. Only the Registration number field is mandatory, fill in the license plate there. It has to be entered without dashes (-) (example: 12ABC3). The input fields Brand, Model, Year of construction, Color, and the checkmarks for Is main vehicle and Company vehicle can be checked but are not mandatory.
When you're done, click on Save at the bottom.
The vehicle (with license plate) you've just added is now on the screen with the linked vehicles. If you want to change the license plate, right-click on the vehicle, click Edit and the same pop-up screen as above will appear. Make the change in this screen and click Save at the bottom.
Last, the subscription needs to be connected again to process your changes. To do this go to the user, click on the gear wheel icon, click on Link to subscription and then just click Save.