Edited my comment to include a link. The chart you've linked only include the "twenty countries currently most affected by COVID-19 worldwide", whatever that means. Probably something to do with current cases or recent deaths. The numbers I found match that chart for the countries which are on it, but Hungary, Bosnia and Herzegovina, Czechia, North Macedonia, and Bulgaria just weren't included even though they would've been higher than Brazil if they were. Edited: as someone pointed out, there's a sortable table further down which gives the same ranking as I quoted, except it includes a couple of additional micro-countries with only a few thousand people.

(Also, Brazil is probably pretty representative of South America as a whole, they just seem to have better testing than other countries there and likely report more of their Covid deaths than others. I know a while ago, there was some analysis suggesting Mexico had more Covid deaths than Brazil with a substantially lower population and was just massively under-reporting them due to missing testing.)