You can select a token from the token inventory, then assign the token to a user.

Navigate to the token inventory

If you know the token's serial number, then enter the serial number to find it

Click the token's actions menu, then select "Assign"

Select the directory, aka the Identity Source, in which the user is to be found

Find the user by name or email address

Optionally, you might want to enter an OTP code generated from the token to make sure that you have picked up the right token

Tick the "Activate Token" option if you also want to activate the token at the same time