The 6680 was released 7 years ago, and is based on Symbian OS v8.0 and S60 2nd Edition Feature Pack 2.
It will only run S60 2nd Edition FP2 installation files, or earlier (S60 2nd Ed. FP1, S60 2nd Ed., S60 1st Ed.)
It will not run anything intended for Symbian OS v9 and later, which means no S60 3rd Ed., S60 3rd Ed. FP1, S60 3rd Ed, FP2, S60 5th Ed, Symbian^3, Anna or Belle will install or work on your phone. (It will also not run any Symbian apps intended for the UIQ platform, or Series 80).