Ask HN: How to promote digital downloads?

I am the new author of my PDF - getting started with passive income building software (link in my profile). Is there a clear cut path to promoting digital products? I have heard people asking me to promote on HN, reddit, answer on Quora, write blogs, create intro videos on youtube. It appears that takes a lot of time in building an audience by providing good quality content on a regular basis. Is there a platform similar to Udemy or Amazon where I can post my digital pdf and the platform takes a cut for the marketing? Any guidance is appreciated. Thanks!