If you have pre-existing TSheets and Square accounts, follow these steps to link them. If you have a Square account but have not yet created a TSheets account, see: How to Set Up a TSheets Account and Link it to Square.
In TSheets, in the left menu, go to Feature Add-ons > Manage Add-ons.
Scroll down to Square, and click Install.
Click Connect to Square.
In the Square window, sign in.
Back in the First we need to connect to Square window, click Next.
Continue making your selections, clicking Next after each, and finally, click Close.