For cPanel, you have the following options to reach webmail:

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.

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.