How do I access cPanel One-Click App?

When you deploy cPanel using our One-Click Apps, the Linode is first provisioned with CentOS 7, the base operating system. Once that's done, automated scripts begin to run to download and configure the latest version of cPanel for you. This process can take around 15 minutes start-to-finish, which is why you saw the script output when accessing the console. Now, to explain that a bit.

Pressing the "Launch Console" button launches the Lish console, an out-of-band way to access your Linode's terminal console for whatever reason. Though, I expect you're looking for a browser login screen.

You can access the WHM login screen via:
https://lixxxx-xxx.members.linode.com:2087/

And here's the cPanel login:
https://lixxxx-xxx.members.linode.com:2083/

For the address, you can either use your Linode's IP address or the fully qualified domain name (FQDN) found in the reverse DNS field in your Linode's Network tab. I recommend using the Linode-given FQDN to start, as the cPanel installation sets up an SSL certificate for this domain. This guide has pictures to point out where to find the FQDN of your new Linode (the rDNS is configured with the domain):

https://www.linode.com/docs/platform/manager/remote-access/#setting-reverse-dns

The login credentials are root for the username and the password is the root password defined when the the cPanel One-Click App installer ran. Once in, I would check out this guide on getting started configuring cPanel:

https://www.linode.com/docs/websites/cms/install-cpanel-on-centos/#configure-cpanel

I am having the same problem. Went through the marketplace to install cpanel. It is not working. Tried logging in with above info as well as other methods found in guides. Also found conflicting information about the subnet mask. I have created about 5 servers so far on linode.