The name of this plant, "Acaena magellanica," is somewhat misleading, because it grows in many places in Chile, not just in the extreme south of Patagonia. as with many acaenas, it does not present major problems for cultivation, requires light soil, is hardy.
The germination of this species is not very complicated, but you should do the cold stratification. You can avoid it by planting the seeds in autumn and exposing them to natural cold stratification during winter time. If you decide to do it "scientifically," soak the fruits for two days in water, then put them into wet sand and put them into refrigerator at about +2 +5? C for about 30 days. Allow the seeds to breathe (ventilate from time to time) and check the humidity of the sand (it tends to dry out quickly, so adding moisture every three-four days is a must). Use poor substrates with good drainage (For instance, 1/2 of sand and 1/2 of garden soil would work fine). The germination usually takes about 3 - 4 weeks.