Hi I am Dave, I will help you with this.
The only versions of Windows 10 that would fit on a 4GbB USB are 9 year old versions from 2015 that are not available for download, and if you install one of those versions none of the current software and drivers will work on that version, you need to get an 8GB USB flash drive and install a modern version of Windows 10 for your PC to work correctly.