Both polar bears and walruses live in Svalbard, which is Europe. I agree that these two animals aren't the best representatives for Europe, but they are European. Same as Barbary macaques, they only have a small part of their range happening in Europe, which is enough to consider them European.
It's not just limited to Svalbard either; the Barents and Kara Sea population, which includes Svalbard, is mostly within the boundaries of Europe. While Svalbard belongs to Norway, the rest is mostly within European Russia.
When we think of Europe we tend to think of more populated areas, but in reality Europe is far bigger than that. You can compare the two maps below.

Walrus - Wikipedia
