nut's a big frigging mess. It's like the bad old days all over again.
ACLs were suddenly deprecated when nut went from 2.2.x to V2.4.x. The format of many of the config files changed. The documentation was never updated, the release notes only say "it's changed" (not how). There seems no way (beyond perfect induction) to figure out what it has changed to
Every HowTo for nut (that I've found, at least) are based on 2.2.x or earlier, including everything
at the nut website
If anybody's figured out how to configure nut 2.4.x, please let us all know.