In the Settings for Google Workspace Marketplace apps, To allow users to install comeen you can select "Allow users to install any app from Google Workspace Marketplace":

Or if you choose "Allow users to install only allowed applications from Google Workspace Marketplace":

You need to add app on your allowlist.

For this, on your google admin, go to Apps > Google Workspace Marketplace apps > Apps list:

On this page click on "Google Workspace Marketplace allowlist":

Click on "Add app to allowlist" :

Search Comeen and click on "Add to allowlist":

The application Comeen has been added to your list of authorized applications.

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