I'm referring to the article 'Estimates for stable minimal surfaces in three dimensional manifolds' of Richard Schoen
In the first paragraph of the proof of theorem 2 the author seems to assert that the universal covering of $ M $ is conformally equivalent to the unit disk (with standard metric). But i have some doubt about this thing. In fact if $ M $ is complete and non compact, its universal covering space has to be conformally equivalent to the complex plane (applying methods of Fischer Colbrie Schoen and observing that non negative ricci curvature implies non negative scalar curvature). Thanks
Indeed, $M$ could be simply the plane, which is its own universal cover. So yes, their statement
needs to be modified. But I think it suffices to replace $M$ with $B_R(P_0)$, which is a non-complete manifold covered by $D$. As other results in the paper, Theorem 2 is local: there is no statement made about the points outside of $B_R(P_0)$.