Formula field to Count specifc

I need help writing the Deluge script for a Formula field that counts the number of records from another Form.

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I need to count the total number of records on a Form in my Application that meet certain criteria. The field is not from the same form as the Formula field so the Deluge script will have to reference which script has it.

i.e. Count the number of records in the 'Donors' form where (Status == "Paid").