"BattleEye Client: Initialized 1.248" (That just means that the client started.)

The reason why the server is kicking you could be anything, perhaps due to ping, some servers are configured so that if you have more than 200 ping they will expel you, it could be because it requires a different version, it could be because it requires X mod, etc, but that message only says that.

So to know why it expels you, try reading at the time of expulsion, if it says something else or go to the RPT file to see if you find the error there.

The RPT file is opened with any text editor like notepad++, notepad, etc.

To find the rpt file, copy and paste the following line into a browser and hit enter

%USERPROFILE%\AppData\Local\ArmA 2 OA

This will take you directly to the folder where the file is, then you open it with a text editor and look in the last lines to see what it says at the time of disconnection