The application is very simple.
Post your PSN ID, K/D ratio and W/L ratio,
as well as anything else you think might be nice to mention.
If you have been referred by a member mention that member in your post.
You have to play with at least 5 members of the clan and get the approval of at least 3 of them.
Based on your Ratios and in-game skills you'll either get put in the casual or tactical squad.