Hello, and thank you for the replies. Turns out that it was the stupid phone! After multiple restarts, cache clearings, etc. I finally persuaded the app to load, and from that point on it was relatively plain sailing, and we are up and running.
I just wish that people would devise systems that didn’t require a degree in computer science. Or a substantial slice of clairvoyance. “Go to menu X, click on item Y”. But what happens when item Y actually isn’t there? One then has to go off on a treasure hunt. Perhaps it’s a function of age (I’m 75) and I come from a time when one simply wired things together and they worked.