A VPN is enough for torrenting, as long as the VPN provider isn't logging. I personally use AirVPN because they have port-forwarding but I've used Mullvad before. I also live in Germany and I've never gotten in trouble.
The guide you linked seems a little outdated, Jackett has been replaced by Prowlarr, which is there to have a central location to manage your trackers. If you plan to use Jellyfin, you should also use Jellyseer instead if Overseer. The *arr services are the ones that actually search for the files to download by using the trackers you set up in Prowlarr. You don't need all the *arr services, I only have Sonarr and Radarr, which are for shows and movies respectively. I also have Bazarr for subtitles. AdguardHome is only for ad-blocking, might be useful to you but isn't needed. Idk why that's even in the guide. Flaresolverr is something I've never heard about and I don't use it, so I can't tell you anything about that. Heimdall is something I don't need because I use YunoHost, which has a dashboard already but it might be useful to you.