I think I get it now. I hope it will help others as well.
させる alone can be translated as "let" or "make."(causative forms)
てもらう is not a causative form in Japanese, but many English resources translate it to "get someone to do sth," which is a causative form. That's kind of misleading. I always think about it as "receiving a favor" and the focus is on the "action", not "person" (～てくれる focuses on the person)
ことにする means "to decide." However, "to decide" means "to influence someone so that they make a particular choice" as well. It's like saying "I want to you to ～”
There's even a causative form in English with this verb, "decide someone to do something."
自分で (myself) やらせて (and let me do it) もらう (do me a favor) ことにしました (I want you to/ I'll influence you to)
私はそれを参考(as a reference) にさせて(and let me use it それ) もらう(do me a favor)よ
Another thing to consider is that させてもらう may sound like you're looking for permission, but you're not really; you somehow know you'll hear "yes, you can do it" from your speaker.
It's not something you'd say to your boss tho. Friends and coworkers, yes.
Would that be ok, If I did it myself? That could be an English equivalent. It doesn't match the Japanese version at all. It's a question, but you somehow know you'll hear "yeah, sure."
The second conditional in English sounds quite indirect and therefore polite. Japanese people like to be indirect and polite and we need a structure that will convey such nuances. If I were to translate Would that be ok, If I did it myself? back to Japanese, I'd probably go for たら or ば because that's a conditional structure in Japanese. However, させてもらう gives off the nuance of "I kind of made the decision that I'll do the thing myself, and I'm just letting you know guys I'll do it. But since I don't want to come across as bossy I will use a structure that will make you think it's a question, but it's not, but still, you'll say yes as I expected." (I'm not sure if that makes sense to you, it does to me.)
It is better to "translate" concepts and contexts, not words. Polite structures to polite structures even if grammatically/linguistically they don't match.
A note regarding させてもらう in anime/manga.
In anime/manga, it can be used in an aggressive, assertive manner as a fancy way of saying that you'll have your way in something, either do it yourself or make the other side do something.