In order to record your playing with INSTRUMENT, you’ll need to make sure to open the plugin within your DAW. There is no recording functionality within the standalone app, this is intended purely for quick access to test new content, install updates, or play around with your favorite sounds.
If you’ve opened the plugin inside of your DAW and are still having trouble recording, please make sure that your track has MIDI input enabled. Please consult your DAW’s manual for more details on MIDI inputs.