I think the answer is actually in your initial posting.
"there is not even a folder like 'temp' anywhere in 'azerothcore' ..."

In worldserver.conf, there is a line whos default is "".
TempDir = ""
I suspect you actually had it set.

I did. I was doing a full reinstall and got this error. I found that line in worldserver.conf, added the directory, and off it went.