Permissions

Apple's macOS Screen Recording permission is a security feature in macOS operating system that controls which apps are allowed to record a content of your screen. It is essential to grant GrabText the access in order to extract selected text from the screen image.
Following steps will help to do so:

Click Lock button on the bottom left, to be able to edit permissions:

When GrabText is run for the first time it will requests permission to record your screen:

Click Open System Preferences button, Security & Privacy window appears:

Select a checkbox next to GrabText app on the right. Quit & Reopen dialog appears:

Click Quit & Reopen, click Lock button to lock security settings:

GrabText will be restarted and ready to streamline your workflow.