Bootcamp just will not install Windows

Okay, so I'm about fed up with bootcamp now. I thought this would be easy but I've had every problem under the sun just trying to even get past step 1.

First, I tried to install it using Mojave, because Catalina and Big Sur discontinued support on 32-bit applications I use. But that wouldn't work at all, so I backed up my mac and installed Big Sur. But still, I can't manage to get this thing working.

Eventually, Bootcamp said it downloaded the Windows support software and created the partition in my Macbook pro, but I don't see it, and my entire disk utility is now used up when previously I had about 100GB free. My storage still says I have 119GB though. So either it's there or my disk space was eaten up by nothing. I got the message that Bootcamp saved the Windows installer but my mac didn't automatically restart. So I restarted it myself, holding the alt key, but it only shows the Macintosh startup disk. My disk utility doesn't show anything new, so there's nothing to eject. I've run first aid on all the volumes and containers, and it didn't find anything at all.

I've tried installing it on a USB but my computer won't allow it because it wasn't made before 2015. I can't try creating a partition again because "Can’t install the software because it is not currently available from the Software Update server" or at least, that's the current error message I've been getting. I've gotten all of them at one point or another.

At this point, I'm about willing to take it somewhere so someone who has more knowledge than me can do it. Also, I am not tech savvy, so anyone that can explain in laymen's terms please.