The download should take very little time as you're only downloading an official downloader.When this is complete run the file, now it should begin the download of the game, the game size is quite large at 2.2 gigabytes and can take a couple of hours depending on the connection speed. The downloader can be minimized, paused, or stopped and resumed at a later time (even if your computer goes off)
When done it will automatically open the Setup. Like any other installation setup it will guide you through it and automatically extract the files (Please note that it will not let you choose where to extract your files, and they will most likely appear on your desktop)
Open Allods and wait a few moments, the launcher should appear with a "Cancel" instead of "Play" at the bottom right,
the patch will then begin. Upon completion there will be a small window that will pop up that says "Restart?" (yes/no) with a timer. Click yes.
TO CLEAR UP ALL DISCREPENCIES THIS IS NOT GOING TO RESTART YOUR COMPUTER JUST THE PATCHER.
After this is done you have a plethora of options at the top right or you can start playing immediately.
NOTE: there are some start up problems still as the game is still new. Check this page for updates on installation