Problem with custom icons using fontello

I’m trying to setup a custom font with Fontello, and I couldn’t make it work. I found the readme section for it confusing specially this section :

Don't forget to import the font as described above

I’ve downloaded the files including config.json from Fontello and wrote this :

import { createIconSetFromFontello } from 'react-native-vector-icons';
import fontelloConfig from '../../../data/icons/config.json';
const MyIcon = createIconSetFromFontello(fontelloConfig, 'mobile-icons');

<MyIcon name="my-notifications" color="black" />

adding the 'mobile-icons' didn’t work, it says

Unrecognized font familly 'mobile-icons'

even though I have the correct font familly in config.json and in the css files associated.

[oblador]

Read under the Installation title.

[oblador]

It’s the front page of this project?