I managed to get all of it by compressing it into a zip folder and extracting it twice. Though is it normal for the program to say "Prologue Demo"? Because this was the version I downloaded from the website up above
For some reason, the displayed name staying as 'Prologue Demo' kept staying regardless of how many times it was changed until I exported it on another computer.
Along with that being fixed, the 29/06/19 version is now just an ordinary .zip - so while it's good you were able to resolve your issue with the previous archive format, hopefully this stops the issue happening to anyone else.