Apologies if this is well known, but in case not, SOAP compulsory vehicle insurance can be bought online and paid for using Paypal. Go to the HDI Seguros page https://www.hdi.cl/ and towards the bottom find the box to click for Seguros SOAPEX. This then takes you to the start of a simple application. We paid about US$28 for 42 days. A PDF can be printed or stored on your phone. Unfortunately HDI in Chile don't do cross border/MERCOSUR insurance, but the SOAP will get you started.