Hello, Welcome to the Forums!
I’ve hosted a few IRL UEFN game jams myself and instantly ran into this problem.
To get anyone else reading this up to speed: To be on an Unreal Revision Control team you must be age verified - and to age verify you must provide a credit card or SSN for verification.
All of my participants have been over 18, but it’s been awkward for me to say “Welcome to the Jam, now please enter your CC or SSN - I hope you understand.”
Using Perforce instead of Unreal Revision Control would be a suggestion. But I think the setup + learning curve would be too onerous for students. (and 90% of adults tbh 
)
My approach would be “There’s still a lot you can do with the editor even without source control”
Maybe have different ‘tracks’ for participants - Where some students focus on using the modeling tools, or others work on particle effects - with the idea of manually exporting their creations into a master project.
My hope is that this is just a temporary limitation and that we’ll have better options in the future. Happy to chat more about jams though!