Install HA on Qnap TS-251

Hi to everybody, just joined the community !! I would like to install HA on my Qnap Nas TS-251. I am very much nooby on these subjects and I really need your suggestions. I cannot find any tips for TS251: I found something for other Qnap models ( x86 ) but I dont think it can suit to my case ( it says to download HA with Docker, but my Nas has got HA with IOT ).
Is there anybody who has done this already ? I feel it is a much harder route than buying a Raspy and do all thru it but I do have a Qnap already and I would like to use it as muh as I can… Tks for anybody who will be able to help me !