Some small supports needed, see pictures. Make sure you block supports in the adjuster.

The 2 plastic parts should have extra walls and infill as it will take abuse. The TPU parts can be normal 2 walls etc.

Use a an 8-12mm self tapping screw in the side to lock the adjuster in place.

1. Place the stopper on the door handle with the hook facing down
2. Adjust the stopper until it touches the door.
3. Push the door against the wall and hold in place on the wall while closing the door. mark the position and mount with a suitable screw/plug.
4. Enjoy.