Cannot run node.js on Ubuntu with another user

Question

I'm running my website with node.js on Ubuntu. When I run with root user it works. But when I run with another user, i have the following error:

"node:internal/fs/utils:348
    throw err;
    ^

Error: EACCES: permission denied, open '/etc/letsencrypt/live/mydomain/privkey.pem'"

I have granted rights on directory /etc/letsencrypt/live and /etc/letsencrypt/archive with chmod -R 755* params, and chown to that user. See how it is at the moment:

"drwxr-xr-x 2 myuser myuser 4096 Sep 22 17:19 mydomain.com.br"

I did a copy of that files in myuser home folder. But when i run node index.js, i have another error:

"node:events:491
      throw er; // Unhandled 'error' event
      ^

Error: listen EACCES: permission denied 0.0.0.0:443"

Is there anything else about permission that i have do grant? Because i don't want to run as root my website.

Thanks a lot.