Bootcamp stuck on copying windows files

So I am trying to work with bootcamp to get Windows 10 on my late 2012 iMac. My current OS is Yosemite version 10.10.5.

I'm not very tech savvy so I only partially know what's going on or what I'm doing.

My boot camp assistant is stuck at copying windows files, and after a while of staying at 50 percent it would give me an error message saying "Your bootable USB drive could not be created. An error occurred while copying the Windows Installation files."

I have tried two different USBs to see if that could help my situation at all, but both have given me the same message.

I can click 'OK' on the message and nothing really happens, it just returns to the loading bar being at ~50% and at that point I don't know whether it has resumed copying or not.

I left it overnight last night, and it remained on ~50% for the whole night, no new progress.

I'm not sure what's going on or how I should proceed from here. Any tips or advice would be greatly appreciated!