hi,
can you copy File with Explorer to USB-Stick ( do NOT use "send to" ! )
if yes you might have a look at ShFileOperation() which "is" the "copy" Part of Explorer
https://docs.microsoft.com/en-us/windows/win32/api/shellapi/nf-shellapi-shfileoperationa
have a look at x:\fwh\samples\dlgfile.prg