Just out of curiosity, how come a question about symfony is offtopic on a programming site?
No idea why the question was closed. The question essentially boils down to:
I'm trying to install a web framework's module. The suggested way in the docs isn't working with the current version of the framework. Help!
That's a concrete, specific and answerable question, about something that's unique to the programming profession:
What topics can I ask about here?
... if your question generally covers ... practical, answerable problems that are unique to the programming profession ... then you’re in the right place to ask your question!
I can only speculate, but I suspect the close voters thought the question was asking about installing some random non programming specific tool, which would make the question more appropriate for Super User. In any case, the closure is incorrect. It happens, we can't get it right every time.
I have reopened the question after a fairly substantial edit was made to clean it up.
If you see a question like this the best approach is to edit it in to shape and then cast a reopen vote (if you are able) or maybe flag it for moderator attention (if you can't).
closed on-hold questions should put them in the reopen queue as well.
The question is not "actually" about Symphony. The OP is asking advice on how to install X. Stack Overflow deals with programming problems, not the errors you face while installing something.
It was closed as off-topic as the OP should instead have asked this on the application's own forums or help-desk.