This post that was quoted has been deleted.
With the greatest of respect ... that, sadly, counts as one of the stupid answers.
The agreement you refer to is a trade deal. It has nothing ... NOTHING to do with the Withdrawal Agreement which is already in effect.
May I politely suggest you research a little - there is plenty of real information available on both lamoncloa.gob.es (Spanish Government) and gov.uk to tell you what applies and doesn’t apply with regards moving to Spain.
In making your answer “with great respect”, you have in fact demonstrated that you are utterly clueless as to the difference between the WA and the currently being negotiated trade agreement ....