If you are hearing your guests say that they cannot enter their credit card details and that the expiration and CVC fields are missing, there are two main explanations for why this may be the case.
What your guests are likely seeing:
What they should be seeing:
1. Your site may not be secure (i.e. http:// rather than https://). The credit card step will not load properly due to security concerns. How do you know if your site is unsecured? Look to the top where the website address field is. It will indicate if a site is secured. Different browsers have different ways of showing this, so the below is just one example.
2. You did not add the Stripe script to the header of your website when adding the widget code. You can find this in the Integration tab of your restaurant listing under Step 1. It only appears if you have selected the Payment Step option.