What version of Premiere Elements are you using and on what computer operating system is it running? Presumed Premiere Elements 12 or 13.
Based on the history of this, this is not a music score download failure, it is rather a "delayed" music score download.
Many including myself have observed that there is a significant delay between the installation of 12 or 13 and the appearance of Music Score
as well as Sound Effects under the Audio Tab.
Can we assume that you have only recently installed the program? If so, give the Music Score and Sound Effects time to get into place. It
may take minutes to hours.
Please let us know the outcome and supply more details as needed to sort through the issue.