Because you looked at the wrong line. The game isn't 512mb big, it does however require at least 512mb of ram to play. I'd recommend digging a bit deeper instead of just looking at a cutout that google recommended to you
Every other link is down besides the two mega links. MegaUp downloads at 100 kb a second while Mega co downloads at 2 mb a second but stops downloading, making you have to wait for hours to continue
because there is an upload size limit. download all the parts and unzip the first one with winrar. [it will automatically pull the data from the other parts! :) ]
Part 1 --> https://youtu.be/27QJDbKXUS8