From Battleground Europe Wiki
Operation of the Mac and PC versions of the game are almost the same. The only real difference is that the Mac version does not use the launcher program, all offline and online options are available from the application menu.
Please refer back to the Quick Start Guide for other information about getting into the game quickly.
Install the game to your Applications folder.
After starting the game, just click the "Practice Offline" button to run the offline version of the game.
The Mac version of the game does not use the same launcher as PC. enter your login information into the fields, then click "Play Online!"