How can I make my style compatible with the Mapbox Countries v1 vector

[Tapwatero]

I'm going to start by saying I'm sorry if this is in the wrong place but I could not find a discord/forum so I thought I'd ask here. I would like to be able to change the colours of different countries like shown in this example with my own style.
https://docs.mapbox.com/mapbox-gl-js/example/data-join/

Any help appreciated thank you in advanced.