Unscrew the top plate.
Keep the 2 screws.
Slide on this part and insert the screws into the 2 center recesses.
You can use 4 additional screws for the edges. The original part has holes for 4 additional screws but does not use them.
It can be a snug fit if your layer height is too large. In that case try to insert a flash while the plastic is still warm.
The print you see was aborted after that damn Thing-o-Matic failed after 25 of 60 minutes. (The usual extruder-jamming when the PLA gets too hot due to an obvious design fault of the hot end.)