RPi4 for long range telemetry over a 4g connection

Hi to all.

I tried setting up a Raspberry pi 4 to send receive Mavlink via the Telemtry 2 port of an Orange Cube.
As I am new to rpi, I followed some Youtube videos like these below.

I am stuck and feel like I should just start over!
Are there any updated guides to install everything on the rpi?
Perhaps the videos are outdated for a rpi4?