usb is backwards compatible 3 works on 2 and 2 works on 3
it just works on the speed of the slowest side, it will work at usb 2 speeds if the hard disk is usb 2, that means around 40 megabytes per second read and 20 megabytes write more or less, values do change alot with some devices and with some types of files
if the usb is 3.1 type c, it will work but you need a converter from usb type c to usb 3, there the usb 2 will be connected and should work as expected