Have you legally obtained the 2017 edition full score? Let us know in the comments below where you licensed your production.
The full production uses a nine-member orchestra designed to handle a wide range of musical styles, from African-inspired percussion to classic Broadway brass.
The show requires a high level of synthesizer programming. The Keyboard 2 book (often the more complex of the two keyboard books in terms of sound patches) is frequently sought after because it carries the bulk of the "orchestral simulation" in smaller productions. Musicians searching for "Pdf 17" are often looking for this specific, hard-to-find instrumental part to understand the patch mapping or to prepare for a regional theatre audition.
If you are a music student
Unlike classical music by composers like Mozart or Beethoven, which is in the public domain, musical theatre scores are under strict copyright protection. The rights to The Book of Mormon are controlled by the publishers (often in conjunction with the authors and the producing partners like Scott Rudin and Anne Garefino).