How to show an Onsite Form to subscribers or non-subscribers

1. First, you need to create a form. If you haven't already, check this article. You can also select one existing form, by clicking on the Campaigns tab from the main menu and then clicking on the form that you want.

2. From the Editor view, click on the Visibility tab, as shown in the picture.

3. From the Visibility view, you can also set your form's trigger, frequency and targeting. 

4. From the Behavioural rules, click on the Subscribers/Non-Subscribers box.

5. After clicking, click the toggle button to enable the rule and click on the box that you wish, to Subscribers or Non-Subscribers. For the rule to be enabled properly, your screen should look like the photo below.

6. Don't forget to click on the Save button to save your progress.