Touch ID replacement question

So in my classes at school in the past week, my two class mates needs their touch id replaced because apparently the touch id keeps failing.

I bought these 2 touch id buttons online thinking to myself it will be an easy replacement but after hearing about it recently, you have to keep the original home button. Is this true?

if so, what can I do to use the touch id's I have ordered? (Haven't tried it yet) Should I return them back to the owner and tell my class mates only apple can replace it or is there extra parts I need to order for this replacement?

I don't want them to come back yelling at me because its bricked because of an error 53 or etc.

Help will be much appreciated.