I have updated all settings from what I've seen online including requiring a pre-payment in settings and still when I go through my website it lets me book an appointment without requiring a credit card.
this article should lay out what you need to do to set up the online prepayment options
https://squareup.com/help/us/en/article/5676-customer-prepayment-for-square-appointments
there are multiple places to enable it
reply back if those steps didn't help.
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