Interstellar was shot on a combination of 35mm, IMAX 70mm, and IMAX 15/70mm film stock. When you download a true 4K Remux (untouched Blu-ray rip), you are seeing the film exactly as Nolan intended.

So you have the 60GB Interstellar Dual Audio 4k file. Now what? Your old laptop will choke on this.

The phrase "Dual Audio" refers to a video file that contains two (or more) separate audio tracks. For Indian audiences especially, this is crucial.