Actually, that download link is to a zip archive containing DOOM2.WAD and the Mac Doom II executable. Someone should probably report it to Softpedia as a warez upload. Download Mac version of GZDoom, throw your doom.wad/doom2.wad into the gzdoom folder, if you want to play any mods use a mod launcher like ZDL or drag-n-drop the mods onto gzdoom.exe (if that works on mac, idk).
DOOM 3 MacOSX Free Download – LZ0
An enormous demonic invasion has taken the UAC, Union Aerospace Corporation, the Mars Research Facility with a storm, leaving behind mere chaos and horrors. Being one among the few remaining survivors, you need to keep fighting with all you have against massive groups of evil monsters until you actually make it out alive. The way out is filled with darkness and dangers, and you have a few weapons – including a pistol, grenades, a chainsaw, and more – to get through it.
DOOM 3 MAC Game is an action game based on a gripping story that is played from a first-person perspective. The levels of this game most proceed in a linear manner and all of them incorporate several horrifying elements. And the scariest of all is the never-ending darkness. Players can hear the radio transmissions at frequent intervals through communication device which also add to the eeriness of the atmosphere, in fact, these broadcasts of certain sounds and messages from the radio tend to unsettle the player. The player is given a PDA, personal data assistant, in the early part of the game, which contains security clearance levels. As a result, players can gain access to certain areas which are usually locked and out of reach using those devices.