You can define permissions over who can create Smart Inboxes either as an administrator or a non-administrator user. Creation permissions do not affect viewing permission. So if a Smart Inbox is shared with a user with no creation permissions, they still can view the Smart Inbox.
Administrators can create Smart Inboxes in the admin menu of the Work Portal. To define permissions on the admin menu, access the expert view in Bizagi Studio, and then click the Security module. Open the Smart Inbox located in the following path.
Pages > Administration > Smart Inbox
You can define the security user groups, roles, or stakeholders. For further information see Security for Work Portal menus.
If you want to restrict the creation of Smart Inboxes from the Work Portal for non-administrators, you can define the security in the following module.
Pages > Cases > Smart Inbox