Can you point me to an online website that can give me more information about professional football in Congo? I saw them at Afcon recently. These guys know how to play. Do they have a domestic league?

There's only one reliable way - use a local site... but don't think about sports magazines or blogs. Go to a bookmaker - https://1xbet.cg/ There is a full volume of information that will be useful for both gamblers and ordinary fans. I myself use this site when there are profitable football matches in the local championship.