You can submit your game from your account individually first. There will be an option in the game page's settings called "Admins". You can add your team members there and follow the instructions it gives you. Itch.io will automatically add those team members to the game's page. Cheers and good luck!
If you further support feel free to join the Discord server here.
These are some steps I found in some old thread with the same question which might help you.
Steps:
1. Enter the project Dashboard
2. Click More/Admins
3. Enter the username and click Add admin
4. Send the agree to link to collaborator
5. Check the "Display as contributor" checkbox