Maybe this is restricted for your role?
If you click on Environments in the Deployment section you might see a Deploy and also a Permissions tab.
If you are convinced that with your permissions you should be able to see it, you could contact Mendix support and maybe they can help you out.
You have to open the specific app first in the developer portal.
Go to https://sprintr.home.mendix.com/link/myapps > Open the specific app > Press 'Environments' in the sidebar. Then you will see a tab 'Permissions'