How does unlocking the achievements work?

Horizon - Xbox Xbox Gaming
1

I’m a complete loser who wants to buy Diamond for a month just to unlock the achievements, anyone know how it works?

2

You save your profile to a USB and then attach the USB to your computer, load up Horizon, use the Achievement Unlocker to unlock any achievements on your profile.

Check out this thread:

3

oh but be careful if you do to much your gamerscore might get reset