This procedure assumes that you have a linked model instance in the host model, and its coordinates are not currently shared with those of the host model.
Notice the button in the value box next to the Shared Position parameter. It reads Not Shared, which indicates that there is no coordinate sharing between the linked instance and the host model.
Because this is the first time that you are setting up shared coordinates between the host and the linked models, a dialog displays, telling you that you need to reconcile the coordinates in favor of the host or the linked model. You need to reconcile the coordinates only once.
Tips on Acquiring and Publishing
You cannot acquire or publish coordinates from a project that has multiple positions using the Acquire Coordinates or Publish Coordinates tools. Instead, use the properties of the linked model. See Defining Named Positions.