You can ignore the first message (about tangents).
The second one tells you something useful - it tells you that FBX exporter can’t handle anything than regular FK animation and you have to bake it. You can bake animation during export time (see “Bake Animation” option).
BTW: if you’re doing direct import (from mb, max, c4d, …) into Unity you can enable “Bake Animation” checkbox in FBXImporter.