Conference delegates and their guests are advised to contact the Australian Embassy or Australian Consulate closest to their home town to inquire what the visa requirements are for their country.
A list of these can be found at: https://dfat.gov.au/about-us/our-locations/missions/pages/our-embassies-and-consulates-overseas.aspx
The organisers can provide conference participants with a letter of invitation to the conference to assist with visa application. Please email your request for letter of invitation directly to: firstname.lastname@example.org.
Please also make sure you inquire about the visa process early, as visa applications may take considerable time (months) in some countries. You can visit the below link to get a tentative overview of how much time visa applications may take from your country and also what is required in terms of supporting documents for your visa application to be successful. You should enter attending a conference as the purpose of visa application.
Please also make sure you inquire about visa process early, as visa applications may take considerable time (months) in some countries.