Bootcamp could not partition drive

Received a factory reset Macbook pro (made mid 2014) in Mac Mojave. I have tried about 7 times to install windows 10 in the computer with Bootcamp, every single time it says "your disk could not be partitioned". I have checked disk utility, nothing wrong. I have done some things in terminal e.g. the /sbin/fsck -fy and others but it says it couldnt recognise part of the command (warning: command -y not recognised, ignoring), and it says nothing is wrong. I would like to try to manually partition the size of the drive I want, but where I find people talking about it, they never go into detail on what to do. Like how do I select Bootcamp to use that part of the drive that I just made for windows? I also need to do the April update ISO, since mac says the USB isnt big enough for the October update ISO even though the USB is 16gb. I have tried to completely erase the USB and format it as MS-DOS, but it couldn't. I tried twice by removing everything from ports except the USB, nothing worked. I have tried making a very small windows size to see if that fixes it, same error. This is getting VERY frustrating, please help.