I hate to be the bearer of bad news. The smart gateway scheme ended over a year ago. OVO then disabled their live usage API which this app relied on. The app currently only fetches in daily readings over night and doesn’t display a live usage feed. Even worse, OVO have changed their API again which stops this app working completely.
I have contacted OVO and mentioned about this integration. If any new beta program around live usage feeds is introduced, I can hopefully modify in the future.