Dear Suzi Traveler, Congratulations for Buying a Vehicle !
All highways in Santiago are toll routes and you can get fines by driving them without a tag.
You can get a daily pass here : https://www.pasediario.cl/ or at a copec gas station or at a servipag paying station. The daily pass is great because it also covers some toll routes outside of santiago. The daily pass also works in some tolls outside of Santiago, when you get to a peaje(payment stop before a toll route) try to go through the tag lane and see if the gate opens automatically.
Another and easier option is to get a TAG (toll road device), you can get it at any "Costanera Norte" office You will need your RUT and contract you received at the notary when buying the car.
Don’t forget to bring back the tag after selling the car or to buy a daily pass before coming back to santiago.
show them RUT and contract for owning the car.
online via HDI seguros https://www.hdi.cl/hdi-seguros-home/seguros/seguros-de-auto/rci/
Name of insurance is RCI - responsabilidad civil internacional