There is a requirement on MacOS Catalina (10.15.7) or higher to enable Bluetooth in order for this feature to work.
There should be an automatic pop-up requesting permission when opening the application for the first time.
To enable the Bluetooth press "ok" on the pop-up.
If you don't see the prompt, please follow the steps below to enable this manually in the Privacy & Security section of System Preferences:
1. Open System Preferences
2. Click on Privacy & Security
3. Click on the Privacy tab at the top
4. Choose Bluetooth from the list on the left
5. Click the lock icon to make changes
6. Check the box next to Scanmarker.