Cant access yunohost using sftp

i got error access denied when trying to access sftp to my yunohost. Is there any configuration or something that i have to enable?

Have you tried to connect in SSH with your user? Which user do you use?
https://yunohost.org/#/ssh_en

By default, only the admin and root users can log in to YunoHost ssh server.

YunoHost’s users created via the administration interface are managed by the LDAP directory. By default, they can’t connect via SSH for security reasons. See here if you absolutely want some users to have SSH access enabled.