Do you have the link?
I don't know how to find the number of arrests, but in Australia there were 4 people killed by law enforcement in 2016/17 and in the US there were 1,536 killed (2019). Australia has a population of 24M, the US 329M, (so 13 times the population). At the same per-population rate as Australia, the US would kill 52 people, and at double the per-population rate it would be 104.
It would seem astonishing that the arrest rates somehow converts to the US only killing twice as many people!