How to Install Form Builder for Sheet
Create new or open any of your Google Sheet.
Now click on "Add-on" option from the menu .
Now click on "Get Add-on" option from the menu
search for "Form Builder for Sheet"
Select Form Builder for Sheets from the search result and click on Domain Install or Individual Install
It will take you to the Authentication window and select your account
click Allow that will complete your Authentication process.
That's It. your installation process is Completed.
Click on "DOMAIN/INDIVIDUAL INSTALL" button
Follow the steps above.