Short answer is that you don't have required permissions to share project/deployments. When you share project/deployment, you assign access roles to the selected targets to control how they can use project or deployment. There are three roles available: Owner, User and Observer.
The following table describes the capabilities to share the project allowed by each role.
This table describes the capabilities to share the deployment for each role.
* Consumer (roles) can make predictions using the deploy API route but the deployment will not be part of their deployment inventory. ** To Consumer or User roles only. *** Can remove self only if there is another user with the role of Owner.