We have two Help Centers, one for México and one for Chile:
https://ayuda.fintual.mx/es/

https://ayuda.fintual.cl/es/

The problem is that articles from Chile rank in Google in México and vice versa. How can we make sure the correct article ranks in the corresponding country? 

From what I´ve read, there is no possibility to implement hreflang tags neither inject code through Google Tag Manager. We still want them indexed in Google so we can also not restrict them to a certain audience.