Can push it in like this, but it comes off after driving.

 

Those are the plastic clip tabs, possibly one of those guys.
i searched plastic bumper tab clip.
Don't have a specific part number but those can be bought off amazon for the cheap and in bulk. a ghetto alternative would be to finesse some zipties to hold it down

 

Thank you.

 

In the bottom of the bumbper is a hole. Check the opposite side to see if it's the clip itsx posted, or a screw. It could be eiter.