Functional Door Assembly

You need to first decide if you are going to constrain the component using constraints or connections. It sounds like you're trying to use connections here. In this case, a single Pin constraint on one of the hinges should suffice to give you the motion that you're looking for. You could select the two axes/cylindrical surfaces on the two components for the rotation axis references, and then select two planar surfaces/datum planes to lock the translation and complete the connection definition. This single Pin constraint will turn the component orange, indicating it is fully constrained. However, the 3D Dragger will still display the rotational degree of freedom as being available, and the component will appear in the model tree with a little open square next to it. Adding a Fix constraint locks all degrees of freedom and will not allow the component to move at all.

Alternatively, you could use Constraints to enable the same motion. However, in this case you cannot fully constrain the component. That is, it must remain purple in the graphics window, also known as "Partially Constrained", or "Packaged". This will show the component in the model tree with a little open square next to it. Essentially, when you see a component in the model tree with the little open square it indicates that there are degrees of freedom still available and you can use Drag Components to move it. For this case you would create a Coincident constraint for the two axes/cylindrical constraints. You would then create another Coincident constraint and select two planar surfaces/datum planes to lock translation. You would then uncheck the option for "Allow Assumptions" in the Placement tab. This would re-enable the rotational degree of freedom around the axis.

You *could* add an additional Angle Offset constraint to control the rotational angle with a dimension. However, this would fully constrain the component and thus not make it available to be dragged using Drag Components.