The installer on the Nevigo site automatically defaults to the latest build (2.3.4 at this point). If you have a valid license you might be able to ask Nevigo support directly to see if they can link you to the older version.
However I would suggest that your professor simply request to have the software updated on their end as the license seems to cover all major 2.x updates for free anyway (I know that's probably out of your control though..).