The executive branch, the "Catalan Government", doesn't have to comply with that petition, because resolution proposals are non-binding. The Catalan Parliament

The executive branch, the "Catalan Government", doesn't have to comply with that petition, because resolution proposals are non-binding. The Catalan Parliament _does_ have real authority, because they have the legal authority to pass/approve laws (which a resolution proposal is not), and those laws are of course legally binding. It's just that the parliament, in this case, has decided not to approve a law but a resolution proposal. Of course, they chose so to cover themselves and reduce the personal legal risks/repercussions for congressmen of approving this so-called "declaration of independence". Also the vote was secret because of that reason.