The old XML image for clans in ArmA 3 is obsolete Bohemia interactive created an easy way to setup your squad image in game called ArmA 3 Units
Step 1: Launcher
Launch your ArmA 3 Launcher, in the top left you should see DASHBOARD
then you should see a tab called MY UNITS yours will look different form mine click the button in the center to go to My Units page
Step 2: ArmA 3 Units Website
You should now be on the ArmA 3 Units website your going to want to press the Login button in the top right corner
Try to create an account using steam if you dont want to just use the regular signup or use facebook
Step 3: Setting up Link with Steam (Skip if you already linked your account with steam)
If you havent linked steam on the main ArmA 3 units page click your profile button at the top and choose Account Settings
Scroll down and you should see 4 options to link social account including Steam click the steam Icon
It will send you to steam to Login and accept the Linking to Bohemia Interactive
Step 4: Applying for the Unit
Now you want Search for the Unit Spartan War Fighters or just click this link
SWF Unit Page and press join under the clan picture to apply One of us admins will accept your join request just let us know
Step 5: Your Done time to activate
Now relanch ArmA 3 and under
DASHBOARD then MY UNITS hit the refresh button in the top right corner of MY UNITS then scroll over Spartan War Fighters you sohuld see a check box in the right corner of the picture check that box and your good to go