using remote repository for backup with borgmatic

I use Borgmatic(version 1.9.5) in order to dump backups (fs & databases). TODO this, I must create 2 backups repositories : local folder and cloud storage. Into my machine, the archive is generated without issue. For remote server case, I have a cloud archive hosted by ovh. Basicaly, here the credentials : - Host Name : gateways.storage. .cloud.ovh.net - User Name : pca - Password : . . Unfortunatly, the archive is not stored into the distant volume. Here an extract of the config file :

repositories:
- path: /data/borgbackup
  label: local backup
- path: ssh//:@/./
  label: remote backup

When I execute the command (borgmatic init), I'm invited to put the password. output :

using builtin fallback logging configuration
35 self tests completed in 0.06 seconds
SSH command line: ['ssh', 'pca@gateways.storage.***.cloud.ovh.net', 'borg', 'serve', '--umask=077', '--debug']
pca@gateways.storage.gra.cloud.ovh.net's password:
Remote: exec request failed on channel 0
Connection closed by remote host. Is borg working on the server?

On remote url, I tried with rsync (same result). Also, I tryed with sshfs (ssh fileSystem) for having a mount folder and procede like a local folder, neither this case: Failed to create/acquire the lock /mnt/backup-cloud/lock.exclusive (timeout). Questions - Do you have any clues about it? - Can I store the password into the config file ? or better mechanism (ssh key) ?