I have got a presentation from my daughters school. It’s locked for printing and downloading.
There shurely must be a way to download it somehow anyways, right?
Taking screenshots is the last resort, but then links get lost etc. I am thinking about saving some kind of web archive, but my tests didn’t work.
Any ideas?
AFAIK, if the file is locked you will not be able to download it.
Maybe ask whoever shared that presentation if they could please remove the download protection -or- send you a copy privately? Possibly could be helpful to explain why you need it too.
If it’s for school, it probably can’t be that Top Secret, right?
That is a solution. But it’s more fun to override the system! 
Screenshots into Apple Photos might let you at least copy the links if the actual url is shown.
Can you print to PDF?
Nowadays, when Apple is OCR:ing everything, screenhoting this is much easier and probably the quickest way unless the presentation is very big.
And no, you can’t print to PDF on a locked presentation.
I don’t remember how (or if) I solved this eventually.