Hi dear project owner, I'm interested in this project but I can't submit my design without your invitation.
Would you invite me to this project, please?

I would appreciate it if you extend the deadline, please.

I’m not sure how to invite you to the project

Thanks for replying. Actually, I had received your invitation and my design is ready to submit.
The only problem is I have finished a few hours after the deadline.
If you contact DC team maybe there is a chance to extend. Many Thanks.

I will be starting a new project tonight with the same brief just about. I can Invite you when I post that one and you can put the design into the new projects

By the way, I've uploaded my design here:
gofile.io/d/By4g0F
Thanks, Chase.