I've looked all over the website, and it seems to indicate that the student version should have Workgroup PDM, as it is included with Solidworks Premium. However, when I open up my student copy of Solidworks, I can't find the option to enable it, nor can I find the PDM add-in.
I looked at the info shown on the SW website regarding the student version there is nothing shown regarding doc management. Interestingly it does state that it includes SW Premium applications (which does include Workgroup). I highly doubt that it is included because doc management is not the same type of application that engineering/design tools are.
Not fully sure if it is included but explore the installation files OR DVD and search for PDM. Also re-run the installation and check if you see WPDM in the list of software to be installed.