That quad card reader you got off of eBay is meant to be able to use 2 cards inside your computer and use 2 more cards through the back of your computer.

If you want something that will mount in that slot in the front of your case, you will need to find one that is specifically meant to mount in that slot.

Most of the ones I have seen use a 3.5" or 5.25" drive bay as those are not proprietary.

Then you have a single or dual 50-pin cable going from the bay to the ISA card.

i am looking for a specific/original IBM part that is engineered to fit inside this computer, not a other company hardware.

Well, that quad slot card is not meant for that chassis. It is meant for the slimline chassis.

See here for information about that card and pictures to see what system that card was made for.
http://ps-2.kev009.com/ohlandl/9533/9533.html#4Slot

i have found the same site, I thought, since I only found this card, that IBM had only built one pcmcia card and was adaptable to many models

Yeah, I was not able to find any information about a different card either. That one is way too short and the slots are not in the correct place to line up with the slot in the case either from what I could tell from the pictures.

My guess is that the case setup you have was meant to have an adapter like the one from eBay that I linked that has a separate card with the cables going to the PCMCIA slot assembly.

Or maybe they do use the same card but there was a cable or extender that went from the card to the slots that are supposed to mount in the front slot on the case.