There are a couple of problems.
Your goin at the wrong time of yr, the schools will be closed.
You’d need to show qualifications in teaching.
You’d need the Spanish equivalent of a CRB check.And a lot of official govt dept finish in the summer months, so you may be too late for that check.
You’ll be in a group of a few hundred thousand people who are already unemployed, so you will need something rather special. A friend of mine just managed to get some waiter work over Easter, there was over several hundred people who applied, he got it as he knew the cleaner.
You listed this in the Official Spain Expat and Spain Forum staff announcement section, don’t take this the wrong way but if you could not work out the work section on this site and post it in there maybe your not suitable for teaching work in s foreign country.