For me, the problem was that after copying my dev site to live, I had not reverted my wp-config.php file back to the dev version. Specifically, there’s a line
define('DOMAIN_CURRENT_SITE', 'domain.name.com');
I should have changed its value from the live domain back to the dev domain, and I had failed to do so. Hopefully this helps somebody else.
The problem is with the instructions provided. There are a lot of tutorials online that talk about how you have to install this plugin manually. They are correct. You also will not see it listed in the list of plugins.
