Far before internet era, publishers print their journals in hard copies and distribute them to subscribers and bookstores. Being a subscriber, you need to pay an amount of money, and they will periodically send the hard copy to your address. Or you can buy individually in book store or journal's office. For authors, before internet era means they need to send their article by mail. All communication are done by mail or phone.
Scientists published their research papers in printed scientific journals, and these Journals could either be subscribed to by other scientists, and/or were located in almost all University Libraries where they could be accessed by other interested scientists.
Not easy. My sister who published 3 books with different publishing houses haven't got a penny. Instead she had to pay two of the publishers to cover the cost hoping the sale will bring some income. Nothing ever came. All publishers gave her many many extra copies to pass around (she could have sold these, but she is a good samaritan). I am sure the publishers got some profit and pretended that they didn't.