First, I want to make it very clear that running MATLink does not require administrator privileges. Enabling a certain MATLAB feature that it relies on does require admin rights (on Windows only), but this feature is often already enabled at the time when MATLAB is installed.
What does require administrator rights on Windows only is registering the MATLAB COM Automation server. This needs to be done only once. The MATLAB Automation server needs to be registered for any program based on MATLAB Engine technology to work (such as MATLink). This may or may not have been done during the installation of MATLAB. To verify if it is registered, first install the MATLink package by placing it in
$UserBaseDirectory/Applications, then evaluate this from Mathematica:
If the Automation server is registered, you should see something like this at the end of the output:
COM server information:
Program ID: Matlab.Application (Version 9.0)
Command: C:\Program Files\MATLAB\R2016a\bin\win64\MATLAB.exe /MLAutomation
If it is not registered, ask your administrator to do it. Is it possible to register the Automation server without admin rights? I don't know. It could be possible, but I don't know of a way to do it. You can at least try running
regmatlabserver and see if it works.
Now what about adding directories to the PATH environment variable? You don't need admin rights to do that. On Windows there are two PATH variables. A user one and a system one. Just add it to the user one. How to do this depends on your version of Windows. There are usually two boxes in the window to set environment variables and the top one shows user variables.