The "Credentials" description

Parameter: Description:
Name: It's just name alias. This alias will be used in 'Servers' page for choose credentials
SSH key If it is enabled, the key will be used, if turned off - the password. Do not forget to download the key to all servers or install the sudo without a password
Group You can set one of the exists group. Group = namespace. Members from one group cannot see servers from another
Credentials You can set username and password(if SSH key is disabled) for access by SSH. Sudo user must be without password
Upload SSH Key Choose exists credential name for uploading SSH key
Key Private key. Note: The public key must be pre-installed on all servers to which you plan to connect
SSH credentials