Installing maps with trails and elevations of Chile & Argentina in Basecamp

I am a brand new user of this forum and a fairly new user of a Garmin GPS, so please be patient with me. My question might be ridiculously simple to answer but I cannot find a straight forward answer (or tutorial) on this web site or on the Internet in general. Some background In the past, I managed to download and install routable maps of European countries. Initially from the Open Street Map web site http://garmin.openstreetmap.nl/ and lately from the Freizeitkarte web site for instance for Germany from http://freizeitkarte-osm.de/garmin/de/deutschland.html The latter are, as far as I know, based on OSM but I like them better because they come standard with elevation profiles. I install the downloaded maps in BaseCamp where I prepare tracks and routes for the hikes I want to do. Once that work is done the tracks and the maps are exported to my Garmin Oregon 700. So far so good. My problem I am now planning a trip to Patagonia and I would like to prepare a number of day long hikes the way I described above. Freizeitkarte does not seem to have maps for Chile and Argentina but I was able to compile and install a combined map for Chile and Argentina from http://garmin.openstreetmap.nl/ . This map does however not have elevations and, worse still, does not have a sufficient level of detail to show the trails I would like to do. I looked for other options and found the web site of Proyecto Mapear. I could download a map of Argentina and Chile from http://www.proyectomapear.com.ar/. This map has some (most) of the trails in Argentina but no elevations. The map of Chile from Mapear, on the other hand, shows only larger roads but no trails and no elevations either. I can find maps • for Chile on https://www.openstreetmap.org/relation/167454 and • for Argentina on https://www.openstreetmap.org/relation/286393 or even • for Patagonia on https://www.openstreetmap.org/relation/1132401 . All these maps are great. They show a nice level of detail, have elevations and show all the trails … but, I don’t know how I can download these maps to install them in Basecamp to prepare the hikes I want to do and to export the hikes and the maps later to my Garmin GPS. I hope a simple method (similar to what I described at the start of my request) is available because I am not a computer geek. Thanks for pointing me in the right direction. Patrick