Spring RTS Engine

I've had spring for a while but haven't downloaded any units for it until today. Not knowing where exactly to put them, I put the .ufo files in the main spring folder. I started a single player skirmish and the game crashed, but before it did, i got the message"Warning too many unit categories 33 missed _____" for "phib" "mobile" and "fort." There were more as well, but they were gone before I could read them. Any ideas?

EDIT: I downloaded the files from www. unituniverse. com

Using single unit additions is highly unrecommended for spring. Make or obtain a mod that has it instead.

okay...