Use the Terms of Service field to request user agreement. While in your Form Editor, go to the Advanced Fields panel and drag the Terms of Service field onto your form.
In the Edit Field panel → Field Text box, change the text I agree to the terms of service to anything you want.
If you want to link to your terms of service (and you probably do!), you can either have them displayed in a lightbox above the form or link to the TOS page on your website.
To use the lightbox, select Show Text in the Link Behavior dropdown list, adjust its width and height below and click on Edit Text to provide your terms of service. To link to your website, select Open URL and provide the web page URL. In this case, your TOS page will open up in a new tab when the link is clicked on.
The words on which the link is placed can be established in the Field Text box, using the tags and .