I've got one for a Pixel 4a here, but the same general scheme should apply: They are double sided adhesive. One sticky side sticks to the clear plastic film and the other sticky side sticks to the colored plastic film. However, the packaging of them should have been better. They were just loosely thrown into the box and some of them came off their supporting film, sticking to the packaging and each other.

Like for many others, this step didn't work well for me. The instructions should really clearly state that you need to pull towards the outside to unclip the motherboard bracket.This is what the clip on the upper right of the motherboard bracket looks like in profile. Also, my spudger tip bent and almost broke. I had to use a small screwdriver to be able to apply enough force to unclip.

I found it very hard to get the opening pick in and pry out the headphone jack. I eventually resorted to applying the heating pack that you also use at the beginning to get the screen out. Then gently push the pick upward inside the hole of the headphone jack to lift its edge up slightly to get the pick eventually in underneath.

Also, when reversing this step, put in the top left corner (from picture in step 41) first. Otherwise it might snag on some plastic mounting post there that can prevent it from sliding all the way down and in.

It's not really necessary to remove the end of the tape that sticks to the motherboard (top end in these pictures). That way, you can easily put it back in place when you put the phone back together.