Make sure Adobe After Effects is open before clicking the 'Connect to Ae' button.
'Connect to Ae' will automatically search for the active After Effects path. Alternatively you can manually add the path to the After Effects application file.
eg. Windows - "C:\Program Files\Adobe\Adobe After Effects 2023\Support Files\AfterFX.exe"
When the application path is found the button will change to 'Disconnect'. Click 'Disconnect' to clear the application path.