(This step can be done before removing the existing top assembly, but is easier after installing it)

Using the metal spudger to hold the split ring open slide it into the mount on the new top assembly.

Keeping the side which has the 2 ends of the split ring either to the front or back, and the flat side away from the camera one of the other side, slide the black retainer clip onto the split ring, with the solid side away from the camera while the clip is the way a strap would hold it.

Repeat the step for the other side.

Reattach the neck strap to the connectors