Is your Archipelegates download from itch, version 26 (shows on download page)? The checksum should match if so. The patch will never work if the checksum fails. Even a single byte difference in the assembly file will result in a checksum fail typically. It's possible there is a compression/decompression thing going on that I can investigate, otherwise, there is no reason for the checksum to fail assuming we have the exact same download (I've downloaded it and tested many times on my end).