For cPanel, you have the following options to reach webmail:
Option 1 – Direct URL
To access webmail through any browser, use a link with the following format:
Replacing domain.tld with your domain name. Enter your login credentials, which include your complete email address and password. Then, click on the Login button.
Option 2 – From cPanel
You can also access webmail from the cPanel → Email Accounts section:
Locate the email account and click on Check email:
From there, you will be able to access your webmail by clicking on the Open button:
Using this option, the email credentials will be already added, and you will be automatically redirected to the email's inbox.