Moving to new server - copying everything by hand but sites unavailable

Can you help me with a permission issue I'm having on the server with mumble-server application?

If you go here you can see the detail of the solution that mumbles gives for this, but I dont know how to do it and I dont know if changing the permissions is a good idea.
https://wiki.mumble.info/wiki/Obtaining_a_Let's_Encrypt_Murmur_Certificate

<C>[date time] Failed to read /etc/letsencrypt/live/mumble.example.org/cert.pem

I tried to reconfigure the mumble-server with the correct path to the fullchain.pem and to the private key, but then I get this error:

<C>2022-05-26 15:47:23.733 MetaParams: Failed to read /etc/letsencrypt/live/chat.pastlife.works/fullchain.pem
<F>2022-05-26 15:47:23.733 MetaParams: Failed to load SSL settings. See previous errors.

I even requested a new certificate for the subdomain chat.* in order to try to avoid this because that worked on another system (ubuntu jammy with certbot from snap).

I cant connect to the mumble server because of this, it was a public server with SSL and now I broke it
Thanks so much for your time