Hi there, one way to work together remotely is to use the “co-editing” feature, which is part of the premium subscription. It allows 2 users to work on the same project on 2 computers at the same time. Please check out question 17 on this tutorial page:
https://www.forum.creaticode.com/topic/447/new-features-of-the-creaticode-playground#anchor17
If you are not looking for such a real-time collaboration tool, I suggest you and your friend work on different parts of this project, such as different sprites in it, then you can merge your sprites into one project, using the export/import functions of sprites.