Install: delete old autorun installation, unzip autorun-test-build-4.zip to the root of your SD card — everything goes into switch/wine.
What changed, how to upgrade from test-build-3 and known issues: see the release thread on the forum:
https://forum.ticoverse.com/topic/101/autorun-test-build-4
Upgrading from test-build-3? Your Windows user folder is now C:\users\steamuser (was C:\users\wine): move saves and settings from switch/wine/drive_c/users/wine to switch/wine/drive_c/users/steamuser. The forum post has the details.
Game reports and help: Game Discussion · Help & Suggestions
Antivirus false positives
Some of the DLLs in this package are heavily patched Wine builds, modified so Wine can run on the Switch's OS at all. This can trip antivirus and scanner heuristics. That's a false positive caused by the patching, not malicious code — the source is in this repository if you want to check it or build it yourself.