The user license doesn't allow the permission: View External Client App Consumer Secrets in Metadata

I am trying to create an External Client App in my oldest personal dev org (ca. 2013). When I attempt to obtain the client id and secret, I get an insufficient permissions error. My user has the standard System Administrator profile which is tied to the Salesforce license. When I search for the new External Client App permissions on the profile they are not there, so I created a custom perm set and gave it the permissions. Now when I try to assign the perm set I get:    The user license doesn't allow the permission: View External Client App Consumer Secrets in Metadata    Any ideas on how to resolve or workaround this?