(The original readme can still be found at README.md, but was woefully outdated)
This fork likely breaks compat with old versions of VS. It is intended for VS 2019, but will likely work with 2017 as well.
AnkhSVN consists of a lot of projects in its solution.
It is assumed that Ankh.VS.VersionThunk and Ankh.VS.VersionThunk.V4 originally exist to maintain compatibility with the .NET 2.0 runtime while moving the main project to .NET 4.x. This makes the architecture more complex at little gain these days, so both projects have actually been moved to 4.x at this point.
VS should mostly figure out how to gather the necessary references through NuGet, with one notable exception: Ankh.BitmapExtractor requires you to manually fetch a few files from elsewhere, probably for licensing reasons (as also mentioned in the comment in its Program.cs).
After building, Ankh.VS15Package\bin\Debug contains (among many other files) a .vsix that will install to VS 2017 and 2019.