Wix Dropdown with Documents

[rbcozad16]

I have been creating a website for a school’s music department and am working out how to add documents to a page, the teachers really want to have it in a drop down list, i have the first two drop-downs set up with data but have no idea how, if its even possible, to do the third. Ill attach a quick example of what she wants it to look like (done in paint so it isnt really a functional example).