This news confirmed by Sony.
Marvel's Avengers

PlayStation and Crystal Dynamics confirmed that Spider-Man will be coming to Marvel's Avengers. That's the good news. The web slinger will be added as a free update post-launch to the game but only if you are playing on a PlayStation. That exclusive bit would be the "bad news."

This news was confirmed in a PlayStation Blog posting. Crystal Dynamics says that Spider-Man will be added to the roster in early 2021 at no additional cost to those that own the core game. If you are upset at the lack of Spider-Man on your non-PlayStation platform of choice, there is still some good news. Another Avenger, Hawkeye, was also confirmed as a post-release DLC character. Hawkeye will be available across all platforms.

Everybody loves Hawkeye, right? Hawkeye is a great substitute for Spider-Man. Right? Riiiiiiiight?

As a small reminder, the beta dates for Marvel's Avengers are quickly approaching. The first beta begins on August 7 for those that pre-ordered the game on the PlayStation 4.