Everything in:
C:\ubb\7-5-5\ubbthreads-7-5-5\ubbthreads-7-5-5
Goes to:
demongov.com/ubbthreads
Except the directories:
"includes", "styles", "cache_builders/custom"
As said:
The install directory is the UBB directory; it wants you to take all of the files from the zip you downloaded here (minus the directories "includes", "styles", "cache_builders/custom") and put them in your UBB directory and then run the install/upgrade.php file