Invoke-SwisVerb access denied when running with non admin AD account

I'm trying to run the following:

$swis = Connect-Swis -Hostname $IPAMServer -Trusted
Invoke-SwisVerb -SwisConnection $swis -EntityName IPAM.SubnetManagement -Verb GetFirstAvailableIp @($subnetAddress, $subnetMask)

It works correctly when the account's IP ADDRESS MANAGER SETTINGS are set to Admin, but not when anything else like Power User. Then i will get the following error:

Invoke-SwisVerb : Access denied

Is this by design? If so, how can we restrict access of the user who need to run these scripts to certain subnets?

Thanks