In the Settings for Google Workspace Marketplace apps, to allow users to install Comeen Workplace 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":
Then you will have to add Comeen Workplace on your allowed apps list.
For this, on your google admin, go to Apps > Google Workspace Marketplace apps > Apps list:
On this page click on "Google Workspace Marketplace allowed apps list" and click on "Add app to allowlist" :
Search Comeen and select Comeen Workplace on :
On the third step, select the users or groups concerned by this change :
The application Comeen Workplace has been added to your list of authorized applications.