This is a good resource for getting e.g. an SSH password from your encrypted controller backup file: https://github.com/zhangyoufu/unifi-backup-decrypt/blob/master/decrypt.sh

In short these are the commands you need to decrypt it (static and old key, so why bother encrypting it at all, Unifi? However, love that it is actually possible to open it):

openssl enc -d -in "network_backup_[...].unf" -out tmp -aes-128-cbc -K 626379616e676b6d6c756f686d617273 -iv 75626e74656e74657270726973656170 -nopad

yes | zip -FF "$TMP_FILE" --out "$OUTPUT_ZIP" > /dev/null 2>&1