I have configured an app script project in script.google.com for developing an gmail calendar add-on. This project is duly linked with a cloud project.
When I am trying to configure G Suite Market Place SDK, "gmail add-on extension" checkbox is disabled under "Extensions".
I have given all the required assets per SDK configuration.
Can anyone please tell me why "gmail add-on extension" is disabled and how it can be fixed?
Google is currently limiting what Gmail add-ons are permitted to be published publicly. You may not be able to select a Gmail add-on extension with Public visibility until you have filled out the Gmail Add-on Submission Information form here: Gmail Add-ons Submission form That starts the process of getting your add-on whitelist for public publication. Once you're whitelisted, you should be able to complete the publishing process.
Ref link: answer from stackoverflow
