Welcome to the forum @pedroeduardo
It would be best if a user with openSUSE Leap helped, if this gets OS-specific… High-level info is:
mono at version 5 or above is required. That lets you run the mono command. The file might be in /usr/lib/duplicati but I’m unsure where yours is. If you have /usr/bin/duplicati-server, examining it with a text editor would probably show, or you could run that script to start the server.
/usr/bin/duplicati is usually a server with a tray icon that shows status via its style and colors.
Starting at boot would be done by configuring systemd, typically done via the systemctl command.
openSUSE:Systemd tips
The systemd Daemon
You’d probably do things like sudo systemctl start duplicati (or stop, enable, disable, etc.)
Examples from other systems:
Installing Duplicati on Linux (Ubuntu / LinuxLite)
How to install Duplicati on Debian Stretch