There are cases wherein the NetSuite email address is not the same as the Gmail address. In order to associate the NetSuite email address with the Gmail address, the addresses need to be mapped against each other.
Steps To Resolve
Step 1: Create a "Celigo Employee Gmail" custom record type.
Switch to Administrator role. Go to Customization > List, Records & Fields > Record types.
Step 2: Look for "Celigo Employee Gmail" and click "New Record".
Step 3: Specify Employee field and fill out the Gmail Address field and hit Save.
The Gmail address is now linked to the NetSuite email address.
Ask your NetSuite Admin to re-allocate your license by first removing it and then re-adding it back. For more on license allocation see this article.