I tried to install the Mix IDE but
MSVCR120.dll is missing from the install package and it won't run. Any ideas what else I could try?
I am afraid that you have hit an issue which know about but haven't had time to fix yet.
We need to run the "Visual C++ Redistributable Packages for Visual Studio 2013" (https://www.microsoft.com/en-us/download/details.aspx?id=40784 ) as part of our install process, to ensure that you get these Microsoft DLLs if you don't already have them. We don't see this issue ourselves, because we all have Visual Studio installed.
Please can you try running this installer yourself, and report back on whether that fixed the issue? Thanks!