OK, that got me connected. There was an update that it installed, rebooted, and then I went through the setup.
I also connected it back to my home network because I only have 5g of data per month on my phone.
Now, whenever I navigate into the Roku Channel, I am presented with a list of titles that are currently available, but if I select any, I get this message:
Cannot access program
This program is not available or has expired.
[OK]
Does this mean anything to you? 
I'm sure I can reconnect using my phone's Hot Spot, but it will eat through my data quickly.