To enable Guest Checkout in your Format Store (bypassing the need to have a PayPal account you need to change a preference within your PayPal Business Account settings.
PayPal Business Account Settings
In your PayPal Business Account tap your name in the top-right corner to access the dropdown options
Tap 'Account Settings'
From the left sidebar under PRODUCTS & SERVICES tap 'Website payments'
To the right of 'Website preferences' tap the 'Update' text link
Enable Guest Checkout
To the PayPa account optional