for some reason the "follow someone" its not working for me

In order to replicate the gif,
You need to go into a weapon ready stance before pressing default T to follow the soldier that you're looking when you're right behind them. If you left click and/or right click you will then let go of the shoulder and be free to move.

This is a simple attach to command so you won't be able to turn your head and if the person leading the stack does sharp turns then it will look janky af. Still a great concept and mod, you just need to time the disconnect is all.

how do you replicate that GIF?

I would recommend using the cameraon command instead of player so that your scripts can be used on remote controlled units like zeus does. player command returns the player but the remote controlled unit is returned by the cameraon command. I am a huge fan of your mod (as evidenced heavily by my all ghillied up yt vid), keep up what you are doing!