Step 1: Go to ftp://www.sonsofexiled.fr/ArmA3/ArmA3Sync/releases and download the arma3sync-installer-1-6-97.exe.
Step 2: Launch the executable and install Arma3Sync
Step 3: Launch Arma3Sync
Step 4: Navigate to the Addon Options tab and click the + button
Step 5: Locate the Arma 3 directory and click Open
Step 6: Navigate to the Launcher Options tab and set the ArmA III Executable Location – if you are running a 64 bit system then make sure to choose the right file (arma3_x64.exe)
Step 7: Navigate to the Repositories tab and click the + button
Step 8: Under Public auto-config url paste the url: https://atlasfrc.eu/a3s/.a3s/autoconfig and click import. When the information has been autofilled, click OK.
Step 9: Click the “Connect to repository” button
Step 10: Select all the mods, and click the “Play” button to start the download
(If you’ve moved the mods from !Workshop to the main directory, skip this step!)
Step 11: Navigate to the Online tab and click the + button and enter the server details
Step 12: Under Join Server, select the Atlas option and Start Game