The @CBA folder included in the 506th modpack has the correct version of CBA_A3 (2.0.0). The CBA_A3 currently available on Armaholic is version 2.2 and is not the version the unit is using. You will need to delete the @CBA folder you have now and extract the one included in the 506th pack.
The issue is not with your instructors. The issue is running an incorrect version of a mod on a unit server. The errors may not kick you off of the server but the error reports will cause server performance issues. Which is not acceptable. Should you try to join an official operation with a CBA mismatch, you would be kicked from the server.
