To remove the blue sheet or not?

I just bought a keyboard replacement (part # IF123-120-1) for my early 2015 retina macbook pro, and in installing the main keyboard ZIF connector its unclear if the blue protective sheet need to come off of the plug on the keyboard. Im used to seeing gold plated contacts, but these are black on top and silver on bottom. the silver ones are covered by the blue tape. Using a multimeter, the upper black side shows electrical conductivity while the bottom side does not, even when i peel back the sticky blue tape. I’m wondering if the tape is there to increase thickness so it stays tight in the ZIF connector or if it needs to be removed. If so, why does it leave a sticky film behind on the silver contacts that appear to not be conductive? Thanks in advance!