Currently, you can only import screenplays that were made in Final Draft 9 or higher (.FDX format).
So if you have a script in PDF (or another) format, you must first convert it into a .FDX file using screenwriting software like Highland.
Afterwards, export it a .FDX file and reimport into StudioBinder.
Before you import the .FDX file, make sure you prep the script by generating scene numbers. Learn more about prepping screenplays prior to importing here.