How to Install Form Builder for Sheet
Form Builder for Sheet is available in Google Workspace Marketplace
You can install Form Builder in 2 ways.
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.
Directly reach the add-on using following link in Google Workspace Marketplace Form Builder for Sheets at Google Workspace Marketplace
Click on "DOMAIN/INDIVIDUAL INSTALL" button
Follow the steps above.