Oliver,
.FIT files can only be loaded directly onto a compatible device, and can’t be uploaded to a platform like Final Surge, Garmin Connect or TrainingPeaks. This is a limitation of those platforms.
You CAN upload your completed activity to Final Surge once completed. See the Q&A of the workout library, but I’ve included it here for your convenience:
Q: Can I upload these workouts into Garmin Connect, Zwift, Final Surge or TrainingPeaks?
A: First, let’s distinguish between a planned workout and a completed activity. The workouts on the 80/20 Workout Library are planned workouts intended to load directly into your compatible device. Once you perform the planned workout, it becomes a completed activity. As planned workouts, these 80/20 Workout Library raw .FIT files can be imported directly into your compatible device to walk you through the workout. Regrettably, these raw .FIT planned workouts cannot be uploaded directly into Garmin Connect, Zwift, Final Surge, nor TrainingPeaks for future planning purposes. This is a limitation of those platforms. You can, however, upload your completed activity into these platforms like any other activity that you complete.
Planned bike and run workouts can be synced from TrainingPeaks into Garmin Connect and Zwift (bike only) as well as automatically to your device if a) the workouts are in the TrainingPeaks Structured Workout format and b) using Garmin Connect AutoSync integration. The entire 80/20 Workout Library is made available to you in TrainingPeaks’ Structured Workout format with an 80/20 Subscription, where you can add the 80/20 Structured Workouts directly to your TrainingPeaks calendar as planned activities and sync them to Garmin Connect or Zwift (bike only). Additionally, our individual 80/20 electronic plans include workouts in the Structured Workout format and the ability to automatically sync your daily planned workouts to both your device and Garmin Connect and Zwift (bike only). TrainingPeaks is not able to automatically sync or export swim workouts, but you can still manually import these swim workouts to your device.
David