Usually, when I see jarosite, it is just a stain, but always as a weathering product of Fe sulfides, where the acid is locally produced.

If it is limonite, then we might invoke a weathering by a small amount of dew of the iron component of the meterorite. But the material is too yellow for limonite. (given the usually "color of mars" caveat.)

If it is jarosite, then we need a source of Sulfur, as there are not iron sulfides in the meteor. Here's my arm-wave: a small amount of occasional morning frost combined with sulfate dust (blowing in the wind) combine to create a small amount of sulfuric acid, which feeds off the kamacite/taenite (Fe-Ni) to create a small amount of jarosite as a weathering product. Just a thought.

The lack of hematite (rust) and the lack of a crater (indicating, to me, that it has been here for some time) speaks volumes.