The Save Emails and Attachments add-on for Gmail is available for Google Sheets, and can be installed by anyone having a Gmail or Google Workspace account.
Open the app inside Google Marketplace and click the blue Install button to add the Save Emails and Attachments add-on to your Google account.
On the next screen that says "Save Emails and Attachments needs your permission to start installing", click the Continue button.
You'll now be presented with a list of Google accounts that you are currently logged into. Choose the Google account under which you wish to enable and run Save Emails and Attachments.
The add-on will now request permission to access your Google account. Click the Allow button to grant the necessary access.
The add-on has now been successfully installed and can be accessed inside your Google Sheets.