-all *arr apps in docker containers using docker compose -tailscale has friendly tailnet name -…magicdns enabled -…global nameservers have mullvad public dns in them

not very confident here, can I just follow this guide (link: https://tailscale.com/kb/1114/pi-hole/) and it works or do I need to change some settings? I notice it tells me to add a custom DNS but mullvad is already in there? how does it know which to use or in which order?