Here's the steps for submitting a scratch game in itch.
1. Make sure you have an itch account. The same account can have multiple submissions. Just make sure that different students have worked on each submission.
2. Have the students share their projects and send links of those projects to you.
3. Go to this website. https://packager.turbowarp.org It will allow you to change the scratch game into an HTML game. This way you'll be able to upload it into Itch.
4. Then you can click submit your project, and follow the website from there. This link has some more detailed instructions if you want them.
https://docs.google.com/document/d/1dLBaXwF_D7sCJV38SjGuMcSDM1GlvTc-No6Wp91L5xc/...
Happy coding