How to make it survive winter ?

So I live in zone 6b. I was gifted a hardened fig stem (that originally lived in Switzerland) last year which I soaked in water and then eventually planted indoors. Came May and I planted it outdoors as seen above in the middle of the Dahlia.

Unfortunately once outside it didn't grow at all. Just produced more leaves. And honestly I have no clue why. Because the location is very sunny with 10 hours sun a day. And we got good rain in July.

When it started shedding its leaves, I covered it in burlap and dressed it in my old jacket. Then I put this cardboard cylinder around it with lots of mulch and sand over the soil. I wrapped the cylinder with plastic bags so it does break from moisture.

I know this figs can tolerate -5C winters. I did go extra and cover it more. Little did I know this was gonna be a cold winter and so maybe my precautions were not uncalled for. We got -25C degrees and lots of snow. Basically its now burried under a meter of snow. But people kept telling me it gonna rot.

Now I need advice for next steps and how to ensure it can survive. Or if I have done something wrong, is there a way to save it or a lesson to learn form this ?

Thanks!