I hesitate to give advice to someone who has been playing the game many more years than I have.
But my take is that the best way to learn OOTP is with baby steps. Don't try to do everything all at once. Confused by things like waivers, contract options, budgeting, etc? Turn off the financial aspect of the game to begin with. Overwhelmed with the minor league system and managing that? Take it off your list of responsibilities and let the AI manage the minors. (Or use a more abbreviated reserve system and get rid of the minors altogether.)
Focus first on the aspects of the game that you like most or feel most confident about. Learn those and then slowly add in other elements to your comfort.
But also I think the best way to learn is by trying and failing. And learning from your failures. Don't be afraid to screw up, especially when learning, as perfection is never an option and you won't learn anything by being scared to play around. It's a game; have fun with it.
As for a PDF, well, your best option is the official manual. Not the most enjoyable thing to read through in it's entirety and certainly could use some tweaking, but a great resource to turn to when you have specific questions or are looking to explore certain aspects of the game. There is a PDF version that was provided by pstrickert:
https://www.dropbox.com/s/mmkcvusbzr...anual.pdf?dl=0
But of course, the hyperlinks won't work in this version.
So might also want to refer to online manual for more functionality.