Website at https://restic.readthedocs.io/en/stable/030_preparing_a_new_repo.html#amazon-s3.

Configure your environment with the credentials for polycloud and your restic repo:

export AWS_ACCESS_KEY_ID=<your_access_key>
export AWS_SECRET_ACCESS_KEY=<your_secret_access_key>
export RESTIC_PASSWORD=<your_restic_password>

Copy a file from your local computer to polycloud:

restic -r s3:polycloud.crowdapis.com/<your_bucket>/<your_restic_directory> init
restic -r s3:polycloud.crowdapis.com/<your_bucket>/<your_restic_directory> backup <path_to_directory>
restic -r s3:polycloud.crowdapis.com/<your_bucket>/<your_restic_directory> restore