Hi Al,
When attempting to share your feature layers from ArcGIS Pro with Portal for ArcGIS, your Portal must have either:
i) a hosting server configuration (e.g., a hosting GIS Server + the ArcGIS Data Store) - this is also commonly called a "base deployment", or
ii) a federated server configuration (e.g., a GIS Server that is federated with Portal), or
iii) both associations as part of your Portal.
Depending on which set-up you've enabled with Portal for ArcGIS, this will affect your sharing options:
i) will allow you to copy all data;
ii) will allow you to share with registered data;
iii) both options will be available.
Once this requirement is met, then you will be able to set Portal for ArcGIS as your active portal to share content to from ArcGIS Pro.
Hope this helps,
