If it's a music jam you want to join, there's the OST Composing Jam that's featured to start next month: https://itch.io/jam/ost-composing-jam-7
It seems to be an annual thing that runs through every July of the year. Here's a link to the one hosted last year and the one prior.
Good luck! I took a look and there are prizes there! 🤤 Well, the prize itself is a feature on the playlist, but that counts, right?