This topic is quite old, fees were higher in BTC (but lower in fiat) at these times. 0.01 BTC per kilobyte means million satoshis per kilobyte, so thousand satoshi per byte. The absolute minimum is one satoshi per byte, so you should divide your $20,000 by a thousand, and then you have $20.
You definitely cannot fit a 50MB pdf in there.
Why not? It will cost at least 50 million bytes, so 0.50 BTC, that could cost around $20,000 you mentioned before. By adding some data to avoid standardness limits, I guess you will end up somewhere between 0.5 BTC and 1 BTC.