i'm not sure how does this work?
the round rubber thingy should be mounted to chassis one. it was glued on it or what?

the absorber is bolted to the rubber.
i dont understand how they fix the rubber to the chassis, i didn't see bolts.
it is glued to the chassis? it cant be like this.

ok, with exploded view, this design is clear to me now.

it pinches the chassis body with bigger bush at its bottom and its top nut.

it looks to me, you need to tighten the nut properly with correct torque to hold them in place.

see the protrusion length of the bolt at top side can give you hint.

measure it with caliper to see the difference.