If you are the owner of the workstation you wish to install the software on and you will be the one that manages it, the single-user installer is the simplest to maintain.
If your workstation is managed by your company and you are not an administrator of it, but they do not manage your CTC tools, the single-user installer will allow you to install and use the tools in most cases.
If your company manages your workstation and the software installed on it, you should contact the manager of your system to get CTC tools.
If you are the manager of the software your company uses and wish to deploy it, the multi-user installer will install the tools for any user account on the workstation.