Typically AIR-TAG's are configured before fulfillment so you'll likely already have a login and password from where you'll be able to find the AIR-TAG in question. Simply navigate to the AIRCLOUD login page, LOGIN and use the search tools to identify and locate the specific AIR-TAG.
If the AIR-TAG is newly installed, it's worth checking and validating the configured data...
1) Check data in your account
2) Edit, update or change information of the AIR-TAG
3) Give others AIRCLOUD access to the AIR-TAG
Read FAQ 'How to create an Aircloud URL & account for your customer and assign the Airtag to your customer'