Is there something I need to configure/register on my Portal end? when I add my Portal to Tile Package Kreator I get an invalid client_ID error from the sign in page.
You do need to add tile Package Kreator as a registered app on your portal. The steps are the same as are described for Survey123 here How To: Add Survey123 for ArcGIS as a registered application to Portal for ArcGIS 10.3.1. The difference is the app id and that you would need to do it for any version of portal (Survey123 is automatically available for portals 1.4 and newer).
Below i have extracted the key steps from the KB article linked above, and inserted the Tile Package Kreator app id.
A. Add and share the Tile Package Kreator app
B. Register the Tile Package Kreator app
C. Change the Tile Package Kreator App ID
Pending rquest for 6 weeks
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