To access a Linux device remotely, at least the standard management agent must have been deployed to that server. After clicking that Linux device in the My devices list, you have a choice of SSH and SFTP in the lower pane. Selecting either option will launch a new window.
Note that if the device has not had any agent deployed yet, double-clicking that device in the My devices list and selecting Remote session will launch the Windows viewer as a default behavior, as the OS is not yet known. The viewer will report that it was unable to connect to the device.
If you select SSH access, a window opens with an SSH session on the remote device. You must provide a username and password to access the device. When you have authenticated, a secure shell session opens on the remote device.
If you select SFTP access, a window opens with a secure FTP view of the remote device (based on an SSH connection). You must provide a username and password to access the device. When you have authenticated, you can use the secure FTP functionality to transfer files between your computer and the remote device.