Unable to build on Windows Server 2016

On Windows Server 2016:

I clone the repo:

git clone https://github.com/PowerShell/openssh-portable.git

I run the build script:

.\openssh-portable\contrib\win32\openssh\OpenSSH-build.ps1

I get the following error (First Bug):

VERBOSE: Start-OpenSSHBuild -NativeHostArch x64 -Configuration Release -NoOpenSSL:False -Onecore:False -Verbose
Checking tools and dependencies
Chocolatey not present. Installing chocolatey.
Start-OpenSSHBuild : Exception calling "DownloadString" with "1" argument(s): "The request was aborted: Could not create SSL/TLS secure channel."
At C:\src\openssh-portable\contrib\win32\openssh\OpenSSH-build.ps1:29 char:5
+     Start-OpenSSHBuild -NativeHostArch $NativeHostArch -Configuration ...
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Start-OpenSSHBuild], MethodInvocationException
    + FullyQualifiedErrorId : WebException,Start-OpenSSHBuild

So I tell PowerShell to use TLS 1.2:

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

I run the build script again:

.\openssh-portable\contrib\win32\openssh\OpenSSH-build.ps1

It takes a while to start the actual build because it is installing:

• chocolatey
• Windows 10 SDK

Then I get the following errors (Second Bug):

 24>c:\src\openssh-portable\config.h(1704): fatal error C1083: Cannot open include file: 'io.h': No such file or directory [C:\src\openssh-portable\contrib\win32\openssh\libssh.vcxproj]
      addrmatch.c
    ClCompile:
      arc4random.c
 24>c:\src\openssh-portable\config.h(1704): fatal error C1083: Cannot open include file: 'io.h': No such file or directory [C:\src\openssh-portable\contrib\win32\openssh\libssh.vcxproj]
 25>c:\src\openssh-portable\config.h(1704): fatal error C1083: Cannot open include file: 'io.h': No such file or directory [C:\src\openssh-portable\contrib\win32\openssh\openbsd_compat.vcxproj]
      base64.c
 24>ClCompile:
      atomicio.c
 24>c:\src\openssh-portable\config.h(1704): fatal error C1083: Cannot open include file: 'io.h': No such file or directory [C:\src\openssh-portable\contrib\win32\openssh\libssh.vcxproj]

Full log here:
Log.txt

Are there some environment variables I'm supposed to set up or another dependency that I'm missing?