Oh no, sorry to hear you're having trouble with this Toby!!
On our 2012 Macbooks, we only need to double click the zip file and the ArchiveUtility extracts the application. We're unfamiliar with any other process (and Macs in general), so troubleshooting may be a bit more difficult.
So, firstly, what year is your Mac and what version is it on? (And no worries about the jargon either!)