Sign in with your email address or the Apple ID that you use with your iCloud account. If the status is Network Offline, make sure that your Mac is connected to the internet, then try again. You can't sign in to with an email alias. You might see a status icon such as a lightning bolt or a warning icon next to your account's inbox in the Mail sidebar, or in the upper-right corner of the Mail window.You can change or delete an email alias, but if you delete an or email alias, you can't add it back to your iCloud account.If you created one or more email aliases for your account, be aware of the following:
In each case, you can sign in to iCloud with either your email address or the Apple ID that you use with your iCloud account. Type your Hotmail password on the Password field, or with the two-step authentication enabled for your Hotmail account, use an app password.
Check out How to Setup your Mac Mail client if you need help with the configuration settings. The first step involves the setup of your mail client. I would try this first to familiarize yourself with the process. Troubleshooting the Can’t Verify the Server with Mac or Apple Mail Steps to setup Trust for Self-signed Certificate.
Review these scenarios to see which one applies to you: In the Mail app on your Mac, choose Mail > Preferences, then click Accounts.