If you really don't have an email I'd call the store and ask. Do you have a stop and shop rewards card? If so then you log in on either on app or website and you'll be able to do the order for pick up there.
You can get a free email from gmail.com or would be useful to register your Walmart online account
You can probably login as a guest but it is good to get an email because it is a reference if something is not delivered.
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