The issues related to logging in to the European PC/Mac megaserver have been resolved at this time. If you continue to experience difficulties at login, please restart your client. Thank you for your patience!
Can't look at the moment, but from the top of my head:
game files are in /Applications/The Elder Scrolls Online
(append "EU" for, well, the EU client)
settings files and screen shots are in /Users/<account name>/Documents/The Elder Scrolls Online
HTH
P.S.: If you meant how to get the game's installer for Mac, log into your account with Zenimax at https://account.elderscrollsonline.com/. If you have Early Access, the links for PC and Mac clients should be in the "Purchased Games" section.
Edited by KhajitFurTrader on March 31, 2014 9:32AM