You can install the 6.1 SSH Tectia ConnectSecure on top of earlier versions. The SSH Tectia ConnectSecure and Connection Broker configurations are automatically migrated to 6.1-level as such.
In case you have made modifications to the configuration files, you can make backups of them before starting the upgrade. See instructions in Backup of Configuration Files.
If you are running both SSH Tectia ConnectSecure and SSH Tectia Server on the same machine, install the same release of each SSH Tectia product, because there are dependencies between the common components.