Setting up Amazon S3 storage is documented by Amazon and in the S3 storage guide linked below.

The IAM account creation process gives you a CSV file containing an Access Key ID & Secret Access Key, which is entered into the Storage location 2 section. You use this account to log into the AWS portal and create an Identity Access Management account ( IAM account). To back up to Amazon S3 storage, you need an AWS account. This backup can be used for file and folder recoveries and downloaded if you need to perform a bare-metal recovery. The cloud backup is safely stored offline and protected from cyber threats such as hacking and ransomware. The local backup provides a fast and accessible backup that can be used for any recovery scenario. This best practice strategy provides cyber-resilience and is our recommended backup type for all servers. Disk to disk to cloud creates a local backup and then replicates that backup to a Microsoft Azure Blob Storage, Amazon S3 or S3-compatible cloud storage destination.

Backblaze server