Kopia docker certificate guidance, anyone?

I am trying to run a Kopia docker (because Synology Drive is just sooo slow as well as such a resource hog) but am running into some challenges with the setup and certificates, both self signed and letsencrypt.

KopiaUI on Windows is working wonderful when using SMB on the Synology, but I would like to setup a Kopia Repository server on the NAS instead, with good certificates and a single forwarded port from the internet

I am able to install the Kopia container, and make it run, link the volumes and map the users. And setup a local backup repository. But I am unable to connect to it because to connect to the reporitory, it needs the certificate as well as the user/password.

Where to find the self-signed certificate, or better yet, how to make it go letsencrypt.