If you or your client is trying to install the LiveFlow extension, but are unable to click on the Install button, it it a Google Workplace Admin access issue.
It is possible your employer - or your client's - has restricted access to certain/all extensions through Google Sheets.
As a test, try installing the LiveFlow Extension in an Incognito browser. If you are still unable to install it in Incognito, the issue lies with your Google Workplace Admin access.
Please contact the Workplace Admin to gain access!