It automatically splits the large ISO file into small parts so the Windows installation files can be sit on a FAT32 partition, which is the only working file system supported by Mac for Windows install. If you are using a newer Windows 10 ISO (after version 201809), then UUByte ISO Editor is the best app for creating a bootable USB on Mac. I managed to create several bootable Windows 10 USBs on Mac (Mojave, Catalina and Big Sur) in recent years. And can quickly complete tasks without any technical requirements. UUbyte iSO Editor is a good choice for computer novices. The whole process won't take a long time. Just download and install this software on your Mac and run it. Suppose you are not interested in the above software.
Generally speaking, the task is OK completed in 15 minutes. iso file in UNetbottin and burn it to the USB flash drive. If you have installed Windows iSO files on your Mac, try UNetbottin, plug in the USB on Mac, and launch the Disk Utility option. But if you are a computer novice or are not know much about CMD, please find another way. If you are good at CMD, it is possible to use CMD to create Windows 10 bootable USB on a Mac in a virtual machine.
How about the boot camp Assistant? Although it does not work sometimes, as a multi-boot creation utility, it can create a Windows 10 bootable USB on your Mac.
