have you ever taught English in an indigenous community? if so, I need some advisory.
Try to learn some specifics about the community and anticipate difficulties that may arise. There may be literacy issues and they may be unfamiliar with the concept of a structured course with progression and tests. There may be other issues which are less obvious- some indigenous languages don't use numbers or organise time in ways we can take for granted, so things which appear obvious to us become culture-specific. I haven't taught in South America, but I believe some indigenous languages don't count beyond three, which could quickly turn a lesson 'how many' into chaos, so getting to know the concepts behind their language(s) will help. Learning a language can be very entering very unfamiliar territory, so guide them into it gradually- give them the most basic navigation tools they will need and allow them to develop confidence.