Tuning a 12-string Kantele

Firstly, hi to you, person reading this message, I tried to search for anyhow similiar topic or any topic related this instrument, but I was not able to find one, thus let me start.

Just yesterday I got myself a new instrument - Kantele (a traditional Finnish string instrument - kinda simmilar to the Zither, or the Harp ... maybe - just to get away some obligatory context). However I´ve got some problems with the tunning. When played, it just does not sound right, so I reversed the tunning shifts and I am back at the start again.

Thus I would like to ask anyone, who has some experience with this instrument to throw away any tip on how to tune it properly. I got nothing to compare it with - as it is my first string instrument ever bought and it is also very specific, I would say.

Withal, ... could I unintentionally break the string? But back to the key.

What is the best way to tune it? I did some Googling and found this https://tuner-online.com/ - will this tuner be usable? In theory should be, right? I have watched few videos, but I still remain unsure of this... .

So, if you excuse an old man for asking foolish question about an old instrument, I would not be saddened.

Thank you strangers for any advice.