The ERFs just contain blueprints. You still need the models to render the objects the blueprints reference. These are stored in the HAKs.
Did you download them all? There are also some workarounds necessary for things to work in the current toolset (files stored in your overrides, terrain, and tile folders).
Double check what you have with what's on the downloads page, specifically the ACC HAKs and the Miscellaneous files.
Official ALFA CC haks:
Moderators: ALFA Administrators, Staff - Technical