One of the Malian emperors under the 14th century either allowed for a naval expedition to go west, or personally led it. What would have happened if Mali had established colonies in South America?
The whole expedition is a bit dubious to begin with : it's essentially coming from posterior Arab chronicles thay may be simply wrongly dated and misunderstood, without mention of it in Mande oral history.
Giving the parallel established with Musa, it's possible to see there a parabole about how the still pagan ruler goes West and get lost forever, and the Islamic ruler goes East to Mecca and gains fame and renown forever.
Basically every evidence is either shaggy sources or weird onomastics.
Now, admitting it was done, I don't think Mande had enough of a maritime culture and technology to really exploit such discovery, clearly without clear motivation, and even more establish colonies and maintain a common domination on West Africa and South America.
They would probably meet Caribbean population in N-E South American coast, and the Amazonian agrarian culture(s) that were pretty much disappearing when Europeans explored the Amazon basin.
Basically, the impact would be similar to Scandinavians in Vinland, probably really minor, except maybe with earlier epidemics being involved.