Problem Installing PostgreSQL 12.1 Win8.1: "the database cluster initialisation failed"
your having an ACL error Access Control List so this is windows security issue

try turning off UAC 

if that fails try running initdb manually
C:\pathtoPosgresq\Bin\initdb -D path\to\data\

doing this manually make sure postgres.conf has the correct path to the directory its located in the data directory and you may need to adjust the service registry entries to the correct  database path or just start postgresql manually

https://www.postgresql.org/docs/current/creating-cluster.html
https://www.postgresql.org/docs/current/server-start.html