1. If you're trying to login to the iCloud website via the Safari browser on your iPhone or iPad to verify your account, you will be unable to do so. You will need to login with a computer browser.
2. To verify that iCloud email is set up on your device, all you have to do is go to Settings - iCloud. From there, you should see your Apple ID in the "Account" section and the listing of Mail, Contacts, Calendars, etcetera, should be enabled to sync to your device. You can also initiate the "Mail" app and see "iCloud" listed under "Mailboxes". Simply tap on "iCloud" and then "Inbox" to see your awaiting messages.
3. If the above doesn't work, delete the account from your device and then reconfigure it.