Multi-fam property. Difficult tenant. How to get appraiser access

[Cee Williams]

I found a 2-4 multifamily property in Brooklyn that I'm interested in purchasing via a mortgage. The problem is that one of the units is currently occupied by a difficult tenant. The tenant doesn't want to give access to the their unit. This is going to make it impossible for the appraiser to come do the appraisal. An all cash offer is not a possibility for me and I don't have the 10%-20% down payment amount to do a hard money loan. I'd like any insight on how to go about this purchase. Is the tenant required by law to give the access to their unit if the owner is selling and needs access to the unit for the appraiser to asses and conduct the appraisal for the buyer? Is this something that is only allowed if it was written in the lease? Does it make a difference if the tenant is on a lease, month to month, paying or nonpaying?

Any experienced real estate lawyers or real estate professional out there familiar with how to navigate this situation?