OSI Affiliate provides you complete custom solution to enable terms of services text for the signup page. There are following steps you can follow to Add Terms Text and then enable terms of services text for the sign up page.
Step 1. From the Admin Dashboard, click "Set Up Software".
Step 2. Under "Settings", click "Terms and Services Text".
Step 3. At this Page you can type your Terms and Conditions and click "Update".
Step 4. Then go back to "Settings", scroll down and click "Show Advanced Settings" link and check the box where it says "Require Terms and Services Acceptance".