Posting on the discussion channels requires a full-paid license for Overwatch. To resolve potential issues with posting on the forums please see this guide:
Hey all,
We’ve received a number of contacts from players who are unable to post in forums outside of Bug Report or Technical Support. Below are some common causes for being unable to post topics.
You do not yet meet the milestones in-game to gain discussion channel privileges. You must complete 10 tiers of the current BattlePass season to gain access to most discussion channels. To post in Competitive Discussion, you must be qualified to play the Competitive Play mode in-game by winning 50 q…