If you have set public access for bucket and if it is still not working, edit bucker policy and paste following:
{
"Version": "2012-10-17",
"Statement": [
{
"Action": [
"s3:PutObject",
"s3:PutObjectAcl",
"s3:GetObject",
"s3:GetObjectAcl",
"s3:DeleteObject"
],
"Resource": [
"arn:aws:s3:::yourbucketnamehere",
"arn:aws:s3:::yourbucketnamehere/*"
],
"Effect": "Allow",
"Principal": "*"
}
]
}