You can also link an asset tag to a unit directly from a unit's settings window (while editing a unit), however, this is only possible if this unit was created from the Asset management section with the type "New unit".
🔔 You can only link asset tags to units that were created from Asset management, using the type "New unit".
Link an asset tag
To link a asset tag:
Go to a unit's settings.
Go to the Asset tag tab.
📘 The "Asset tag" tab is only available if you have access to the menu
Settings ➡ Asset tags.Click the ADD ASSET TAG button.
Click the drop down menu and select one of the existing Asset tags. You will be able to see if they are
Available or already
Linked to another unit.
🔔 If you choose an asset tag that is already linked to a different unit, this will cancel the link with the other unit and replace it with this unit.
To submit your selection click the checkmark button
(to cancel and choose a different one, you can click the 
button).
When it's done, click the SAVE button at the bottom.
Unlink
To unlink an asset tag:
Go to a unit's settings.
Go to the Asset tags tab.
Press the bin icon to delete it.
Click the SAVE button at the bottom.