Unable to install or upgrade to Membership Pro 2

The instructions for "Upgrading from Membership" found in the Usage section of the Membership Pro 2 plugin page are not working for me.

There is no Update button in 'WPMU DEV > Updates' and since I cannot get the new plugin to install it's not possible to get to 'Membership2 > Settings'

My only option is to Install Membership Pro 2 and that results in the following error:
Destination folder already exists. /.../wp-content/plugins/membership/