Spanish politics is a little complex. Various regions can be fairly autonomous, somewhat like the US, and have altered their demographics to achieve political outcomes as we have come to expect in say, Minnesota for example.
In this RAIR Foundation article, a clear and excellent summary of the basics of Spanish politics is made which allows us to put the VOX party win in the region of Catalan into perspective. And its no small victory given the demographics of the region, and the tactics employed by Catalan Left and Islamic groups.