Editing a music book

I am using Scrinver to write a book for music instruction. I have over 300 pages of PDF files all written in manuscript paper. This is the Meat and potatoes of my book. When I copy and paste the PDFs from the research folder, the quality severely drops. I have imported the files into my research folder and they look great, but I’m not sure how to make a final product.
How can I have the PDFs added to my draft in great quality in order to create my book?