How can I configure Twitch so that my viewers can use the BetterTTV Emotes?

The title says what do I need for this?

They can do that as well, as far as I know?

No, because my mod told me that he couldn't write something like MonkaS, Pepega, etc.

You have to go to the website of bttv (and preferably afterwards FrankerFaceZ, then you have more) and add shared channel emotes to your channel, with bttv you can add up to 15 and with FFZ up to 25 without paying

Anyone can use the global emotes from bttv and FFZ anywhere, but MonkaS, Pepega etc are channel emotes