It doesn't work like this, like you intend to do it. Parsing text from web-page directly in ABAP is possible, but cumbersome and inefficient.
Usually currency rates and other indicators are consumed via web-services/XML, that are provided by financial institutions, and Banco Central de Chile is not an exclusion.
Here is the page where they explain how to use their web-services, and even provides an example (real example, Karl!) how to consume this web-service in your application.
Consuming web-service in ABAP is not as much complicated than in C#. Here is the step-by-step guide:
https://blogs.sap.com/2013/07/29/consuming-webservices-directly-from-abap/