Launching an educational portal is not illegal per se. You can launch a website which gives reviews and information about the colleges in India regarding their admission process, the important dates, infrastructure of the college, placement, etc.
I think a legal action can only be taken against you firstly, if you put up erroneous information regarding the details of college like important dates for admission, courses offered, etc which misleads the students or parents who refer to your website for getting information about the colleges. Secondly, I think if you are writing a negative review about the college without any proper verification or proof then the concerned college might file a defamation case against you.
Therefore, I think launching an educational portal does not invite any legal action as such but yes you should be careful about the information you are putting up on your website regarding the information and reviews about the colleges.