I'd suggest authenticating users with Steam API (link & more info below) instead of Bohemia account.
Why should users be authenticated via Steam instead of Bohemia account?
- Every Arma 3 owner has Steam account
- Only few Arma 3 owners from playerbase have Bohemia account
- So many services require their own personal accounts nowadays which is super annoying and decreases the interest of users drastically – using convenient way to authenticate users would be a major advantage to make the service more popular