I have a related question (won’t repeat here) but I think that wiki is outdated as Audacity 3.1.x per release notes is supposed to allow more recent versions of ffmpeg libraries to be used.
I agree - the instructions seem to be incorrect. On my machine, after first checking with Windows Defender that there was no virus, I double-clicked on “FFmpeg_v2.2.2_for_Audacity_on_Windows_64bit.exe” (no need for ‘(1)’) which then took me to step 4, and the following steps went smoothly.
So Peter, if you are listening, change step 3 from
Left-click FFmpeg_v2.2.2_for_Audacity_on_Windows_64bit(1).exe to launch the installer…
to
Double-click FFmpeg_v2.2.2_for_Audacity_on_Windows_64bit.exe to launch the installer…