Many countries’ citizens only need an electronic travel authority (ETA) to enter Australia as a tourist or to attend a conference. You can check your eligibility for a visa through this wizard and check the option “attending a conference or expo,”
https://immi.homeaffairs.gov.au/visas/getting-a-visa/visa-finder/visit
You can find out more information about the ETA and how to apply here:
If you do have to apply for a visa this can take anywhere from days to months of waiting for an appointment depending on your country of residence, so we recommend that you apply for your visa as soon as your presentation has been accepted and you have registered for the conference. If you do not have an accepted presentation and need a letter of invitation for your travel you may request this with your registration for the conference.
More information on visas and travel to Australia can be found here:
https://www.australia.com/en/facts-and-planning/visa-and-customs/australia-visa-and-entry-requirements-faqs.html
