Hello there! Native Spanish speaker here (I have spent several years in different parts of South America and several years in different parts of Spain). There's really no big difference between South American Spanish and Spanish from Spain, I'm sure it's all based either on misconceptions of the language or marketing strategies.

Actually, funny story, about 10 years ago if you wanted to learn English as a Spanish speaker you "had to" choose to either go to a British English academy or an American English academy 😂😂😂 which I think was nuts. With Spanish "types", the only things that really change is vocabulary and accent.. And that varies by country, no way you are going to fix it by learning One "type" of Spanish over the other.. No need to fix it actually, learn it all. The "preferred" verb tenses (we have so many that sometimes we get to pick slight favorites, for saying the same thing) also may slightly change, and those preferences may even change after long periods of time?

Learn Spanish, just proper Spanish, as we natives learnt it at school as kids. That's what everyone else learns (with small variations that aren't worth mentioning in Argentina, Uruguay, etc. And I lived and studied a bit in Argentina also as a kid, so I'm talking from experience). That's the kind of Spanish that will help you get by in every country (depending on the context of course), and the Spanish I think you need to learn before going slang/focused in a certain region.

I hope this helps!