Hello @sssch-1481
Is it possible to ask the customer to check to see if allow reseller access is turned on.?
Here is a link to community post that details the steps to check and enable it if this is the issue.
https://community.geotab.com/s/article/How-to-enable-Reseller-Access?language=en_US
If you have any questions please let us know.
Thank you
Jason