This feature is currently in Beta, so to opt in, go to the Gear Button > Beta Features and find Require RTO / RTR Fields in the list and click Yes, then scroll to the bottom of the screen and click to Save your settings. Once this is done, the settings you see below will be available.
You can get to this part of the system by clicking on the Gear Button on the far right side of the blue Admin Toolbar and then clicking on Settings > POS > Rent to Own.
If you click the Configure button for this setting, you will see a panel like this one pop up, and you can click on the fields you see to highlight them in red, indicating they will be required:
You can do the same thing for RTR contracts, with slightly different choices available:
You can similarly set required fields if you are using Finance Contract functionality:
And lastly, you can set required field for Customer information whenever you create a new customer. This will be for any data fields you see on the first tab in the Customer's profile, the Details tab. Furthermore, any custom data fields you may have created for your customers can also be made to be required fields with this functionality.
Once you have set your preferences for each of the tabs, click Save at the bottom, and then be sure to also click Save at the bottom of the main RTO Settings tab.