How/why do old games like Ocarina of Time, a seemingly massive game at the time, manage to only take up 32mb of space, while a simple time waster like candy crush saga takes up 43mb?

A large chunk of a game's size comes from things like textures and audio files. Older games had very small, simple textures if they used them at all. In contrast, newer games tend to use high-resolution images that take dozens, hundreds, or even thousands of megabytes just by themselves.

Likewise, audio in old games was pretty simple. Older systems synthesized sounds, allowing the game to just supply some basic instructions to control them. Now, audio is typically recorded and stored with the game, making the overall size larger.