You're ok. In theory, NOTHING is needed. Tape is a bad idea, because it can interfere with the necessary metal to metal seal of the ferrule, and on the threads could interfere with proper tightening.
A little lubrication on both the ferrule and threads will ease assembly but more importantly, will make future disassembly much easier. Light oil is ok. I often have used plumbers faucet grease, or white teflon paste, which is non-setting. Do not use conventional grey or black dope, which will set up.