Hi Nirang,
The
h5p.com is the commercial site where H5P provides software as a service. Try creating account in H5P.org. Though this allows limited number of interactions, it will be good enough to start experimentation.
Also, there is a difference between "Open Source" and "FREE". Open Source means the creator has shared the source of the created material with you. This will enable you to build on top of the original and bring in customizations. For instance, as you know the NPTEL lectures are in creative commons. This allows you to take any NPTEL video and do modifications as you want, say like doing a Gujarati Dubbing over an English video. However, if you were to ask someone to shoot the video for you in Gujarati, you will obviously have to pay the charges for video recording. Even though the original content in English is still available for free. The OpenSource community gets the financial support by offering open source software as a service.
Use H5P.com if several of the faculty in your college are interested in creating materials like this. You can take an institution account and find the most convenient plan that will provide you the required service.