First, to share a project between different clients (accounts) you need to have Agency access.
To share a project between different clients:
Click on the cogwheel placed to the right of the Project Name
Select “Duplicate Project to Clients”
Give the Project a new name
Select which clients you want to send the Project to in the drop-down list
Press Send Duplicate
The clients that you shared the project with will receive a notification of “Incoming projects”. The users in the client can Accept or Reject the project.
If the project is accepted the user needs to choose where the Project should be saved. When the project has been saved the new client has a Copy of the original project and can start editing and adjusting it to their specific needs.