It was a an unsupervised election that was considered illegal or invalid by the Constitutional Court, the European Commission, international observers and even the Consejo de Garantías Estatutarias, the highest consulting institution in Catalonia, which was created by the same Catalonian government that organised the elections.

Even if you accept the results of the election given by the regional goverment (90,18% voting for independence), most people against or ambivalent towards independence stayed at home and did not want to participate in an illegal election. As a result participation was 43,03%, which means that 38,8% of the eligible census voted for independence, and that's according to the same goverment promoting the independence vote. I'll leave it to you to decide if that is enough to declare independece.