To clarify, there is no official ARM64 ISO for Windows 8.1 available to the public. Windows 8.1 on ARM was specifically released as Windows RT
Always verify file hashes via Microsoft’s official MSDN (if you have a subscription). windows 81 arm64 iso install
Install Windows 11 ARM64 or Windows 10 ARM64 . Both provide official ISO downloads via the UUP dump website or Microsoft’s Insider Program. They run x86, x64, and ARM64 apps natively or via emulation. To clarify, there is no official ARM64 ISO for Windows 8