I'm trying to run the demo on my 2013 MacBook Pro and this is the message I get every time I attempt to run the program via the launcher:

Name: hit3.ogg
URL: http://resources.download.minecraft.net/ad/ad126e435cca94054bf0d616301799a105526cde
Error details: Request error -324: ERR_EMPTY_RESPONSE
Filename on disk: ad126e435cca94054bf0d616301799a105526cde
Path: /Users/dev/Library/Application Support/minecraft/assets/objects/ad/ad126e435cca94054bf0d616301799a105526cde
Exists: false

I've tried reviewing past users' posts with this problem and the same answer appears, however the given answer is only able to be used by PCs.