Artly doesn't seem like a good word in English. But why not? If you can add ‑ly to the end of the noun saint to make saintly, or to the end of friend to create friendly, or to the end of father to make fatherly, why can't you add ‑ly to the end of the noun art to creat artly?
The answer seems to be that the only nouns to which you can add ‑ly to create an adjective must be human. So brotherly is fine, as are womanly and ghostly, but not *carpetly, *bookly, *catly or *horsely.
This is, of course, different from adjectives becoming adverbs: it seems you can add ‑ly to pretty much any adjective to create an adverb, so you have happily, slowly, lazily, dangerously, sleepily, cautiously, superciliously, artfully, etc.
But, in contrast, the ‑ly suffix that converts a noun to an adjective seems to be much more restricted.
Are there any exceptions? I guess worldly and lovely, and probably a few more. Also, there seem to be plenty of human nouns which don't allow a ‑ly suffix: *auntly, *bossly, *scientistly, and many more.