Apple - Is it still possible to get @icloud.com email address?
The steps seem strange, but first you must create your appleid using a non Apple address (note that if you already have an @icloud, @mac, or @me email address that email address is already an Apple ID)
Once your Apple ID has been created, on the device go to Settings > iCloud and flip the mail switch on, you will be prompted there to create your @icloud.com email address.
Alternatively, you can go to setting and go to mail. From there, add account and choose iCloud. If you choose "create Apple ID" at this screen, for whatever reason, it will allow you to create an "@icloud.com" email.
source Apple kb
Using a Mac:
System Preferences -> Internet Accounts -> (Maybe you need to click the +) -> Select iCloud on the right -> Create Apple ID -> Follow the steps
Also note that after entering your birthday, you should select "Get a free iCloud email address".