Check first if you see the "Addon Manager" menu on top, under the "Addons" menu.
If you see the menu, but no buildings, then it's surely a scenery conflict or a library issue.
If you don't see the menu, first check the "Troubleshooting" section at the end of the fsdt_install_guide.pdf, found under fsdreamteam\zurichx folder installed under the FSX root folder. If, after following all the suggestions found there, you still don't see the Addon Manager menu, then report back.