To ensure that customers accept the terms and conditions of your eCommerce store (e.g. payment terms, order processing expectations, etc.), it is always recommended that you get positive consent from online shoppers at the time of Checkout by adding a required "checkbox". Please find below the steps to add this checkbox at Checkout:
Go to your store Control Panel > Settings > General.
Got to the "Legal Pages" Tab.
Change the status for "Show 'I agree with Terms & Conditions' checkbox at checkout" from Disabled to Enabled.
Now the customer will need to agree to the terms and conditions by filling the checkbox when they complete an order at the Checkout page.
NOTE: Please make sure that you have already setup your Terms & Conditions before activating this Checkout requirement.