So with Oracle starting to charge for commercial usage and updates of Java SE, I was looking for an alternative for our Unifi Controller. I ran across a comment in the Ubiquiti forums somewhere that said using Amazon Corretto works very well. So I decided to test it, and that is absolutely correct. Before installing the Unifi Controller, simply download & install Amazon Corretto version 8, which is a no-cost, multiplatform, production-ready distribution of OpenJDK. If you are using Windows 10 x64, be sure to download the Windows x64 version. After Corretto is installed, simply run the Unifi Controller installer. It worked flawlessly for me, which I was quite surprised.