Hi Rowley,
Thank you for the question, and happy to help.
We currently do not support the M300 RTK DAT files as DJI has encrypted these files differently from the other supported models.
Our recommended method of upload flight logs the M300RTK is with our Android mobile app. Our app is able to extract the .txt flight record that is stored on your device and upload it to your AirData account. The .txt file is much smaller than the DAT file located on the drone and it is able to be automatically uploaded with our app.
I hope this helps, and don’t hesitate to reach out with any further questions!
Best regards,
Trevor