If you experiance problems with the order process, please contact the respective reseller:
Since macOS Mojave you will need to give permission to applications to be able to record audio from audio interfaces. To give Boom Recorder permission, go to System Preferences ▸ Security & Privacy ▸ Privacy ▸ Microphone and check Boom Recorder.app.
This is most likely happening due to an audio file created or modified by any other application being in the Boom Recorder's audio output folder. After moving the audio files away from the audio output folder, Boom Recorder should start back up normally again.