The gateway endpoint is better to use https://gateway.storjshare.io instead of regional, this way your customers will have an access from nearest gateway instance to their location.
if you used Fastly and their VCL snippet, then you should provide values for variables:
set var.accessKey = "YOUR_ACCESS_KEY"; # Change this value to your own data
set var.secretKey = "YOUR_SECRET_KEY"; # Change this value to your own data
set var.storjBucket = "live"; # Change this value to your own data
set var.storjGateway = "https://gateway.storjshare.io";
This error mean that it cannot access the file you have specified (it cannot find it).
In this case you probably did not specify the bucket live in the configuration or provided an Access Key and Secret Key doesn’t have an access to these files (the encryption phrase doesn’t match the phrase used during upload or permission issue).
You can check the permission issue and correctness of the used encryption phrase, if you configure AWS CLI with these credentials and try to list a bucket.