Have you tried? The MS Media Creator creates a USB to install 64bit version of Windows 10, I don't believe you need a 64 bit system just to create the install media.
BTW, I found this.
When creating a bootable USB device, I am getting an error about bootsect
To make the USB drive bootable, you need to run a tool named bootsect.exe. In some cases, this tool needs to be downloaded from your Microsoft Store account. This may happen if you're trying to create a 64-bit bootable USB device from a 32-bit version of Windows. To download bootsect:
1. Login to your Microsoft Store account to view your purchase history.
2. Look for your Windows purchase.
3. Next to Windows, there is an
Additional download options drop-down menu.
4. In the drop-down menu, select
32-bit ISO.
5. Right-click the link, and then save the bootsect.exe file to the location where you installed the Windows USB/DVD Download Tool (e.g. C:\Users\username\AppData\Local\Apps\Windows USB DVD Download Tool).
If you did not buy Windows you can download bootsec.exe form one of numerous sites online such as this. (BTW I don't know the safety of this site)
https://gadgetsregion.net/bootsect-exe-download/
6. Once the file has been saved, go back to the Windows USB/DVD Download Tool to create your bootable USB device.