During checkout, why is the customer skipping the payment step? I have a situation during the checkout process where the customer is skipping the payment and moved directly to the fulfillment state.  I'm using the Commerce PayPal module.
Here's my checkout flow: /admin/commerce/config/checkout-flows/manage/default

What's odd is the PayPal buttons display when I'm logged in as Admin, but not when non-admin:

I haven't found an option that looks relevant on the permissions screen, nor have I found a configuration option anywhere.
The order type is configured to use the correct checkout flow (Default).
With Commerce Paypal, I ran into the same issue.
I believe the fix for me was to the move the Payment Information (currently disabled) into the Order Information section. Might also work if you move into Review or Payment section, not sure.
Also, since you're using Paypal, I think you need to disable payment process.
Here is my working setup. Note: I didn't want users to login nor register.