Nothing in your report indicates GSX had a problem during the installation.
I'm not sure what do you mean with "a message stating GSX not installed". Are you SURE you are installing GSX, and not just the Stand-Alone Addon Manager.
In any case, the message might not be a problem if you ARE installing GSX now, because if GSX is not there yet (because you are installing it), it doesn't need to be updated. Read below.
followed by a whole bunch of files that stated they were not installed either.
Not very clear. If you are referring to the progress bar report, saying that (for example), "xpoi not installed", this is just saying "since you don't have XPOI installed, I'm not going to install or download an update for the files needed by that product", which would be more clear, but nobody would be able to read it as a progress bar label that updates quite fast but, of course, it's a totally normal message.
If, instead, you are referring to something else that looks more like an error message, please clearly indicate the precise, exact, text of the error message.
nothing appeared in the addon menu.
This is an entirely different issue, which is not strictly related to the installation, and might happen even if the installation went with no errors, since it's never a GSX problem, but it's always caused by something else.
And, since I already replied to you in another, identical thread, please do not post twice the same, identical, question in two threads, because it makes the forum unnecessary confusing to follow for everyone.
I'll direct you to the post I already replied to you here, about missing menus:
http://www.fsdreamteam.com/forum/index.php/topic,12870.0.htmlDecide if you want to reply here or there, but don't make two identical post for the same issue.