Domain verification during development

I am developing a toy DApp that uses zkpassword for proof of personhood. I am following instructions here. I come across an error related to my choice of domain. I do not yet have a domain for this DApp (infact, I intended to use static github pages site as I did with another DApp).

I have tried various test domains to try to get a test working in development. I have tried w3schools.com, mitrydoug.github.io, and even demo.zkpassport.com. Each time, the following things happen during the iPhone verification step:

1. the “Continue” button has a spinner for ~10 seconds

   

2. I get the following “Domain not verified” error:

   

My guess is that I need to acquire a domain to get things to work. I have a few questions about this:

1. how does the zkpassport app know that I own the domain?

2. what steps does zkpassport app take to verify the domain? what conditions do I need to satisfy to get this step to work?

Thanks in advance for any help!