First, be sure AirParrot 3 is closed.
Open Console from Spotlight in the menu bar.
Press the "Clear Display" button in the Console.
On macOS 10.15 and newer you will need to select Start for the logs to start populating the Console display.
Open AirParrot 3 and re-attempt the action you're having trouble with.
Return back to the Console and type AirParrot in the Filter field. Copy the lines of logging that are visible.
Paste the output of the Console log into a text file (using TextEdit or another text editor application). Attach that log file to a ticket and submit it here to help us better diagnose your issue.