First you download and patch the DAOC client from the real DAOC website: http://darkageofcamelot.com/sites/daoc/files/downloads/DAoCSetup.exe So download that, run it which installs Live DAOC. Run that so that it patches the whole live game.
Once that's installed and patched, you drop the Phoenix files you downloaded into that folder and then run Phoenix.exe (which you just dropped into that folder) to run the game. I make a short cut to phoenix.exe on my desktop.