Click on Your contract.
Click on Users.
Click on Flexible Engine console users.
Click on Add user.
Fill-in the form with the details name and email of the people you want to grant.
Grant privileges to the user on Flexible Engine console.
When adding user, you have the choice between "Guest" and "Admin" roles.
Guest: can see the infrastructure (VMS, buckets, etc.) and start/stop/restart VMS
Admin: Can do everything such as provision new infrastructure and managed services