Hello, and thank you for choosing just answer.
I think the best way to get Win 98 to run, would be to use an emulator. AKA....virtual machine.
Not sure if bootable USB was available when 98 came out. SO that may be why its not working. You may have to create the bootable CD instead.
Also a potential issue with the HDD, while you partitioned it....may be a culprit.
Your RAM is too much, but shouldn't be an issue. a 32 bit OS, can ONLY address 4GB of RAM. just FYI. Should NOT matter though.
I think you can solve this, by burning a CD, and booting and installing from that, INSTEAD of the USB drive.
Or you need to be sure you are installing the OS properly, on the right drive and partition so on, and so on.
But, I think a virtua machine would be the easiest, and it works just like the original....probably faster, as you can use more resources.