You should have gotten an email from itch.io with instructions on how to enter your claim. The email, on my end was titled "[itch.io] The GameDev.tv Game Jam 2022 - Free Course For All Submissions! - Congrats on Your Jam Entry! - Here's How To Redeem Your Free GameDev.tv Course." Use this to search your inbox, trash and spam folders just in case the email was misplaced.

If you still cannot find that email, you'll have to contact one of the hosts to have that email sent out again. If I recall correctly, they did mention they'll provide instructions for people who may not have gotten the email. As it's possible itch.io could miss some people in the process. If you do find the email and submit your course, remember it's first time they've done an event this big with this many submissions. So please be patient and give it some time to process.