Step-By-Step:
Step 1: Click on the Gear icon in the top right corner and choose Tee Sheet Settings from the left menu.

Step 2: From there, toggle the Print Cart Agreement Receipt on.

Step 3: Scroll to the bottom of the screen. There you will see the Cart Agreement Receipt Input. Type your cart agreement policy here, and click save.

Note: The cart agreement will print out when a rate with a cart is sold.