The scramble for Africa took place in the latter part of the 19th century. By then, Spain was a fucking shell of what it was during the glory days of Charles V. Spain never recovered from the French invasion and occupation during the napoleonic wars. On top of that devastation, and losing most of its overseas colonies shortly after, it went through a civil war or two in the 19th century as well. Long story short, Spain was in absolutely no position to be colonizing anyone. Even today, Spain can't really support itself as a "modern cosmopolitan" European nation without financial support from the EU.

Because they literally owned the other half of the world with actual resources.

After having been terrorized and colonized by Moores and other Africans for centuries, they understood not to invite that into their lives again.

the weren't stupid. They had slave ships and learnt from that alone.

Because the pope and Spain and Portugal had a deal. Thats why Brazil speaks Portuguese. Everything left of the line was Spain everything right was Portugals. Spain found resources and injuns. Portugal found a bunch of jungle and niggers. Nobody wanted niggers. Until massive sugar cropping in the Carribean started I the 17th century niggers were not a commodity.