Flyingfluffypiglet: Unless you've sorted it out since, if no download/space issues, there is a possibility of file corruption on Gog's end and you could either contact Support (but which could be slow responding due to heavy workload) or PM directly a Blue and ask them to pass on a request for the games' files to be checked/tested.
That's always possible. Some installers will check file integrity and some won't, might be the size of the game (
often games in multiple parts get checked while single-installers aren't)
Beyond space, could also be a drive issue, if you haven't done it in over a year, i'd do a sector check, maybe scan for bad sectors. Long delays could be when the drive's internal CRC checks and the sectors don't match for one reason or another. Or maybe the drive itself is having issues. Who knows, maybe rebooting the computer could clear something that removes the issue.
I'll download the game and do an integrity check and give my 2 cents from my end.
Though if this file was downloaded a while ago and not the current version, verifying it's a gog courrupt file is less likely...
edit: MD5 sum
9461944dc47338e614b9961abeb313a4 *setup_terraria_v1.4.1.1_(41973).exe
Didn't see an option to do an integreity check. Nor asking the executable options gave me anything for integrity checks.
Installing, halfway through it's seemingly paused... but then it probably is trying to install DirectX and other runtimes as no doubt half the package is dependencies. Given another 2 minutes and it finished.