Setup user

It's a good practice to not running root for non administration task. telegram-cli doesn't run if you try to run it as root (If you are connecting via SSH to a VPS, chances are you are logged in as root).
To set up a new user, for example: iza:

adduser iza

This command should set up user info eg. password.

Then, add newly created user to sudoer group

adduser iza sudo

Now logout from current session and log in to the new user that you set up (or logout and back in).