Can I do this from outside Australia?

Bonusbank is a matched betting site designed for people in Australia and New Zealand. If you don't have an address in either of those countries you will get very little benefit from joining Bonusbank.

You may be able to make money matched betting in the country where you live but it will depend on the local gambling laws and the kind of offers available. 

If you are in Europe or the Americas we recommend checking out NinjaBet. They have content available in Spanish, German, and Italian, plus sites for Brazil and the USA.  For the UK the main options are OddsMonkey and OutPlayed. For everywhere else you can use a search engine to look for options closer to you.