First Login
After setting up gotify/server you can login to the WebUI. When first launched an initial account is created so you can log in. If you have not overriden the defaults in the configuration, use username: admin password: admin.
Once you have logged in you can create your own user(s) and, if desired, delete the default account (after creating a separate administrator account). You can also remove any username/password overrides in your configuration, as they are only used to initially create this account.
If you choose to keep the default account be sure to change the password so it is not admin!