First of all can I just confirm you followed all the instructions from the docs and have added credentials in the dashboard?
Second, are you using the correct bucket, ap-southeast-2 (Sydney, Australia) is in the examples but your bucket might be in another region.
Lastly, if it is a permissions issue, this is the best set of permissions we’ve been able to lock things down to so far:
See how you go with these suggestions and permissions and post back if you still have issues.