Activate your smart trainer sensor. With the CABLE connected to the CABLE Util app, go the menu and select Scan for ANT+ Sensors.
Select FE-C and any other ANT+ sensors you want moved to Bluetooth (Heart Rate, etc.). Then tap on "Save Sensors."
In the ANT+ <-> BLE Assignments tab, select the FTMS service and make sure the FE-C profile is selected. If you have a secondary speed or cadence sensor that you would like to use in addition to the FE-C smart trainer, you will want to highlight them in the FTMS service as well.
Once the profiles and services are selected, select Save Assignments.
In the BLE (out) tab, you can verify that your sensor setup is sending out workout data.
Finally, close the CABLE Util app and open your fitness app to add your CABLE as the sensors.