Confluence Cloud throws 'This add-on cannot be installed without the Atlassian Connect framework.' when installing connect add-on

Summary

When trying to install an Atlassian Cloud plugin the following error is thrown:

This add-on cannot be installed without the Atlassian Connect framework. See our documentation for more information.

Steps to Reproduce

1. Try to install the Google Maps plugin from https://<instance-url>.atlassian.net/wiki/plugins/servlet/upm/marketplace/search?q=google%20maps%20for%20confluence

Expected Results

Plugin is installed

Actual Results

The below exception is thrown:

This add-on cannot be installed without the Atlassian Connect framework. See our documentation for more information.

Workaround

Go to 'Manage add-ons' at https://<instance-url>.atlassian.net/wiki/plugins/servlet/upm and enable the Atlassian Connect plugin then try installing the plugin again.