Spring RTS Engine

hi, i didnt have much time lately and missed a couple versions, so i downloaded the full installer of aa223 and tried it out; however, when i try to build one of those "intrusion detection systems", spring crashes and says the .3do's for those bildings are missing.
How can i get them/install them and so on ?
(tried search; didnt get anything helpfull )

Then post it in the AA thread instead of starting a new one.