Is 26-175 the missing part for my window?

Please see attached images. We are missing the part that goes in the bottom left and right corners of the bottom half of this CertainTeed double hung window. We just purchased this home (built in 1920) so I have no idea when this window was installed or who installed it. Because it is missing the hardware at the bottom, the only part keeping it in when you lift it up are the plastic clips at the top. We would love to be able to put a window AC unit in this window and we need the missing hardware to do that. Well, I have 8 pictures to upload and it's only letting me upload 5... argh. We are missing the metal "pin" that goes into the U-shaped hardware in the window frame.

Thank you so much!! Do I need to order one or two? Like does the part come in a pair for left and right or do I need to order a quantity of two? Thank you.

Okay, I got the part in the mail last week, but there were no instructions about how to install it and there were no screws that came with it. How do I know how to install it? Does it just snap in our something? It doesn't seem very intuitive given the shape of the hardware and the construction of the window and the frame. Thank you.

Okay, so I just went to the product page for this part and read the following:
"Helpful Tip!
This part does not include new fasteners. Do not throw away your original screws, you will need them for the installation of your new part."

Um, this is not helpful in our situation at all because our Pivot bars were missing in the first place so we have NO screws. Ugh. Why would the new part not come with screws???

I would love to finally be able to open this window.

Since we have no screws and cannot install the part...can anyone recommend the proper size block of wood I could go get to prop the damn window open then???

So disappointing.

Good Afternoon,
No we do not have an identical window in this home. We purchased it in June. It was built in 1920. Some of the windows are original to the house and some have been replaced. None of them seem to have been replaced at the same time. We have NO way of knowing what size screw will fit this unless you can offer some helpful suggestions.
It is very frustrating to finally have the right part (I think. I don't even know because we can't try it yet without screws) and still not be able to use this large window, which is the only window in our kitchen and the only window (besides the laundry room window) on the first floor of our home in which we can install a window AC unit (right now we have one in the laundry room with two fans poorly trying to bring it to the front of the house).