Sorry for the delayed response – priority support does take priority and I haven’t been able to get over here to www.remarpro.com for free support as often.
Yes, the premium extension does still work and can be used. It is available to premium support subscribers. However, as I mentioned, it is not really a recommended method.
There is a set of code snippets on the premium support site that describe how to customize to allow login with email OR username. I have updated this post to be freely available to everyone (including users who have not subscribed to support) because this is going to be phased into the core plugin in the near future. So in the meantime, until that is completed, you can use this customization to accomplish the same thing:
https://rocketgeek.com/tips-and-tricks/log-in-with-email-or-username/
For those that do not know how to use code snippets, there is a general “help” post on the site as well that describes how to use custom code snippets:
https://rocketgeek.com/basics/using-code-snippets-from-the-site/