Okay, this is the part where my head explodes:)

My first goal is to get a good desktop browser app.

I tried using your link : http://rayshobby.net/apps/sprinklers/ using both Chrome and Firefox from a Mac Pro.

I plugged in as my IP address
and used opendoor as the password

Just spins and never delivers a web page. Could it be that you most use a mobile device?

Second question: what does it mean to run it on the Pi? Run what on the Pi. I thought the program and station parameters were already stored in the Pi and the web interface merely accessed that data.
I did follow the instructions on Github, but that’s where I got lost on which server or device was in control.

Thanks for the continued help and patience.