Microsoft allows you to download official, time-bombed developer VMs (usually for Edge testing), but those expire after 90 days. For permanent use, you must supply your own valid Windows 8.1 product key.
If you acquired a legitimate Windows 8.1 VirtualBox image (.ova or .ovf), here’s how to use it: windows 8.1 virtualbox image download
Have questions or found a better source? Share your experience in the comments below (but no illegal links, please). Microsoft allows you to download official
A: No. Windows 8.1 is x86 architecture. M1/M2 Macs use ARM. You would need emulation (UTM or QEMU), not VirtualBox (which doesn't support ARM hosts for x86 guests well). windows 8.1 virtualbox image download