I've downloaded a transition but when I unzip the folder all i see is .mov extension files

I’ve downloaded a transition but when I unzip the folder all i see is .mov extension files. I am unable to see the .motr or .localized file extensions.

What is your process to install plugins (transitions, effects, generators etc. in final cut pro ?

Most probably the file is meant to use as video file overlayed over your footage to hide the cut. Also, if there is a second, black/white .mov, this shall be used as Luma Matte. Do a google search on how to apply luma mattes with your editing software (in this case final cut pro)