Hi @Thibaut_Cellier, welcome to the community 
You’re quire right, user management does not allow sharing workflows or credentials between users at this time unfortunately. So at present to share a workflow you’d need to share the JSON code/file of the respective workflow. You can download your workflow through the Workflows menu in the left sidebar:
That said, I do know our product and engineering teams are working hard on improving the user management functionality, maybe @sirdavidoff can share some more details on where we currently are with this?