The bucket needs to be set to public, either via updateBucket() or by going to Storage on supabase.com/dashboard, clicking the overflow menu on a bucket and choosing "Make public"
RLS policy permissions required:
buckets table permissions: none
objects table permissions: none
Refer to the Storage guide on how access control works
Examples
Returns the URL for an asset in a public bucket
res = supabase.storage.from_('bucket_name').get_public_url('test/avatar1.jpg')