MongoDB query searches questions

So, I have been asking tons of questions about a project and so far is coming OK…

About MongoDB… I am using MongoDB Atlas.

1, Where can I get some good courses to learn MongoDB?

  1. I created an index in MongoDB Atlas to do an autocomplete search, and I might also include a compound search with it… apparently I only get a certain amount of indexes available depending on the tier that I am using… Question… Do I really need to be creating indexes in order to be doing searches on MongoDB? the price/cost of the tier will easily go high up on just creating indexes (creating code) to be able to do searches…