Time to remove the earpiece connection cover. You will need one of the plastic piece as well as some long tool like the spatula from the kit.

There are two small clips on each side of the cover that you have to reach to be able to slide it out. After having inserted both tools, you can pull the cover. You might have to use a decent amount of force (and thus why we removed the cover of the band at the beginning). Wiggling it out did the trick for me.

Note: They are most likely the most annoying part of that guide. Sliding them over is pretty tricky. Take your time. The cover are quite flexible so it should be ok.