reasonably, it should be possible for you to paint over the oiled surface with linoljefärg. it is generally recommended when painting outdoors surfaces that you first apply a coat or two of only linolja before painting it. so from that perspective, it's only a good thing that your cabin has already been oiled. just remember that when painting with linoljefärg, you need to paint with really thin coats, or the paint will crack as it dries.
I have only painted with linoljefärg indoors myself though, not outdoors. so my knowledge in this specific case is only theoretical.