IT IS POSSIBLE to share / download pdf, zip rar and other types of files by default.

Look at my screenshot:

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1. Dont distribute other people's materials as your own work.
2. Share with knowledge
3. Knowledge should be free - because it's essencial for humans.
4. Dont try to make money on knowledge (except cost of media etc..)
5. Sharing ONLY for money (piracy) is bad thing.