The instructions for setting up the Unifi Controller on ARM do not cover ARM64. The documentation states that ARM64 is not supported but hints it can be setup manually. The documentation also states that Java 8 is currently required. The following is therefore clearly in unsupported territory but so far seems to work fine. The internet has numerous references and resources but they weren't all easy to find and the ones I read required some modification for my configuration.
Note for the future: double check versions and source documentation if these instructions are dated. Also these instructions are specifically tailored for Ubuntu. See original references for other platforms.
Last update March 25, 2021