A customer is instructed to use a terminal to start stash - when we ask them to install git and try again, git may have modified the PATH yet this is not picked up unless they restart their terminal.
Alternatively, If they are on a mac and have XCode - it will have a /usr/bin/git and the default git at /usr/local/git/bin/git will be either behind it or not in the PATH. Fixing this requires a high level of understanding of how the shell works.