I have never messed with the udev rules or made a
symbolic link to serial telemetry modules. I don't think it should be
necessary. It is necessary to add your user to the plugdev rules unless
you want to run via sudo.
When you plug in the device are you sure you are getting the correct name.
You can check what the device's name is by monitoring the /dev folder before and after plugging in the device. You can also check by running dmesg in terminal right after you plug in the device and seeing what the last device is.
After making sure you
know the device name I would try connecting with cutecom and see if you
can read messages coming from the autopilot.
I have always used FLIGHT USB-serial @57600.