Can't access the plugins page

Greetings. I have a staging server that does not have a public IP address, running a fresh multisite install of Wordpress Version 4.7.2. All multisite features seem to be working, but I am having issues accessing the wpmudev-plugins section from the WPMUDEV dashboard in my multisite install...eg:

https://some.privatesite.staging/wp-admin/network/admin.php?page=wpmudev-plugins

I just get an error message saying "Sorry, you are not allowed to access this page." I'm sure I'm logged in as the main admin. I have checked and made sure the plugin files are owned by the web server user/process and have proper access permissions. Please advise.
Thanks.