We are currently using SSDT to manage our database solutions and handle deployments. Sadly our databases are not compatible with the newer versions of SSDT so while we make the necessary changes to bring them in line we need to use an older version.
Our developer software isn’t well managed and we lost the installers to the supported version. Microsoft unfortunately only have the latest version available for public download. However if you have access to MSDN you can get to the previous versions which might get you out of a bind.
Hopefully this will save you the trouble of looking all over the web as I only stumbled upon it by chance.