I disagree somewhat with David's advice.
Assuming that you had a thorough conversation and did your own checks as well you should not reject the booking now that an acceptance is underway. The blockage is temporary and will not damage your statistics. If they don't complete in the 24 hour time frame you calendar date will open up and all will be well. They can continue behind the scenes and reapply if needs be.
What you can do for the future is to discuss with enquiring guests who they arre and the purpose of their travel and then encourage them to get their account details complete before sending in a booking request. Of course if they have sent in the request already, well then, encouragement and guidance through the verification process is one of the ways that you can begin to provide your first hosting services. ....🙂
I hope this is reassuring to you. @Steven69.