If they have access to the internet, there is no requirement for WiFi. 

It’s curious that you say the speakers are not able to reach the Sonos servers to be able to be set up. Are you running some type of VPN, or special DNS blocker, or virus protection of some type?

Is the S2 app able to ‘see’ the speakers? Is it only when you’re trying to set up the system that you’re told there’s no WiFi? Or is it that the S2 controller can’t see the speakers?

One other note. As indicated in the instructions, a desktop controller (PC or Mac) does not have the ability to set up new, or add speakers, this task must be done by a mobile device. 

You might be able to get an Ethernet adapter for your phone or a tablet so you could use it for setup.

You could add your own WiFi using a travel router and not have to pay the ISP charge.

 Set up can’t be doen with the Windows or Mac app, so you need a phone to set up the system. Since you have no wifi, your phone correctly mentions this. So, as stated by @Stanley_4 you need a way to cable connect your phone.

Depending on the wifi capabilities of the network you could also choose to only subscribe to wifi for a month, giving you the time to set up your Sonos system.

Buy a cheap WiFi access point. Use it for setup with the mobile. If it offends the senses, turn it off afterwards. 

Airgetlam/Bruce

VPN, DNS blocker, and virus protection are all currently off.

I do not know if the S2 app is able to ‘see’ the speakers or not because the S2 app on the computer will not progress beyond “wifi isn’t connected.” So I don’t know if the S2 controller sees the speakers?

This flip Phone does not allow for apps to be downloaded on it. I do not want a smart phone. Does that mean I will never be able to set the speakers up?

As has been indicated, in posts here, on the product packaging and in marketing blurbs, you can not use the desktop controller for setup of any Sonos system.

However, I would think you could easily have a friend with a mobile device, either a tablet or smart phone, come over and set the speakers up, using that device. Once they’re set up properly, your desktop controller would be able to connect to them and play music. 

They are here now with their phone... they downloaded the app... and it's saying it needs to be on a wifi network. I cannot have wifi. Everytime I'm around it it does something to the bullet fragments in my brain and I start hemorrhaging inside.

Return it.  Sonos requires WiFi.

Sonos only really requires wifi for set up and some set up changes. As you have been told you will need wifi for the first steps at least and not having wifi will possibly be a bother in the future. You should ask yourself if you really need this.

If you cannot have wifi for financial reasons (as you stated first) of medical reasons (second) an do indeed want Sonos, you could have other people set up the system when you're not there (tips for how to do this are mentioned abpove) and have them disable wifi as they leave.