Display Condition: Show on X devices
Want your popup to only show for those who are on a desktop computer, or for those who are on a mobile device? With this display condition you can do that.
When editing your popup, you want to go into Display Condition.
When there you want to scroll down to find Show on X devices, turn it on, then in the dropdown that appears in the middle of that row you can select what device this popup appears on.
After you have selected the device, you can close the Edit Display Conditions (top-right corner) then save / publish the popup.