Hello @marcelo and welcome to the forum!
If you mean how to drive the Duplicati GUI directly over the Internet, don’t… The web interface is not security audited/hardened, and all HTTPS does is to provide connection encryption to whoever’s in.
Duplicati webserver https with selfsigned certificate is one example of how you could add HTTPS for whatever it adds in a less risky environment. For Internet, local access from remote desktop is best.
Remote Desktop Manager looks like a third-party (not Microsoft) tool, otherwise for any who are using Windows Remote Desktop on the Internet on older Windows versions, patch now to avoid BlueKeep.