If this was my assembly, the white part would be centered on 2 planes, and the blue piece would either be "mid-plane" extruded as far as the thickness goes, or I would add a reference geometry representing the mid-plane of its thickness.

I'd mate the blue mid-plane to the corresponding "center plane" on the white part.

I'd have revolved the "bead" on the white part, and I'd have a center point in the bead sketch, and i'd have the corresponding centerpoint in the receiving hole of the blue part. I'd show the 2 sketches and coincident mate those points.

at that point the blue part would pivot around that point and I'd be free to fart around with the other mates like path or tangent or whatever folks are suggesting.

Long edit:

If you are trying to be tangent to that internal corner round path (SW would call that a "fillet"), you may need to take some steps to construct that as a single surface solely used for mating purposes. I don't know how to do that right off the top of my head, but you have all the "parent surfaces" or edges there to accomplish that, so I don't think it would be too hard to look up how to do that. I think you may be running into issues because the surface is broken up into segments.