DP Sync is asking me to map a shared parameter file?
DP Sync requires that a shared parameter file be mapped for your project so if you do use the plugin to create parameters across multiple families, they get created and scheduled properly within Revit schedules.
An example of this would be that you want to add "Model Number" to 10 Revit families. Without DP Sync, you would either have to go into each family and create these parameters individually, or you would create a project parameter. DP Sync allows you to create this parameter for all families at once and allows for it to appear correctly in your Revit schedules.
Check out this article from Autodesk that goes into more depth on shared parameter files here.