fwiw there are tools to remove the copy protection / "unlock" the pdfavailable on github, like this one[1] for windows and a number of them[2] for *nix based on qfed[3] or ghostscript

1: https://github.com/abatsakidis/PDFDeSecure

2: https://www.google.com/search?q=remove%20pdf%20copy%20protec...

3: https://github.com/wilfredwee/wilfred-TILs/blob/master/comma...