Ok I got it, but I had to create a directory structure like in the error message
\devtools\mserver-v86c\
The version of mserver I downloaded from the link in the Ted2Go documents tab is MonkeyXFree84f and there is not devtools directory. I had to copy the mserver_winnt.exe from the \bin to C:\Monkey2-v1.1.01\devtools\mserver-v86c\
Where MK2 keeps the templates for “env_windows.txt”? I tried changing the mserver path to this MX2_MSERVER=”${MX2_HOME}\devtools\MonkeyXFree84f\bin\mserver_winnt.exe” but it still points to C:\Monkey2-v1.1.01\devtools\mserver-v86c\ so I had to create these directory C:\Monkey2-v1.1.01\devtools\mserver-v86c\ and manually copy the mserver_winnt.exe from the C:\Monkey2-v1.1.01\devtools\MonkeyXFree84f\bin to C:\Monkey2-v1.1.01\devtools\mserver-v86c\
Now emscripten is working.