There currently isn't a way to customize the checkout page on your Square Online website to add a checkbox that asks your customer to acknowledge your business' terms and conditions.
We do, however, have a pop-up feature that could work as a workaround. You could use the age verification pop-up and customise it so it asks your customers if they agree to the terms and conditions when they visit your website. See the example in the screenshot below.
Choose your pop-up type and select the button to open the pop-up editor. You can customise the pop-up’s style and content, as well as edit settings such as display frequency or scheduling.
Build and customise your pop-up and select Publish to see your changes live. Publishing your pop-up will also publish your website.
Note: Using certain pop-ups requires an upgrade on your Square Online site.
