Q:

Can't add hotmail.com address into Gmail 5.0

I tried under KitKat and Lollipop on my Nexus 4 but I can't add my old account.  I also tried both manual and automatic setup, but same result: credentials are incorrect. 
Any solutions about this?  Should I have entered different parameters during the manual setup? 
EDIT:
POP3 with default parameters: server hotmail.com, port 110, security STARTTLS
IMAP with default parameters: server hotmail.com, port 143, security STARTTLS
Exchange, which doesn't give the possibility to change any parameters

A:

Do you have two-step verification enabled on your hotmail account?  If you do, that extra layer of security can trip up GMail.  You'll need to create an "App Password", which should be a setting in your Hotmail settings.  
From Microsoft's Two-step Verification FAQ:

Some apps (like the mail apps on some smartphones) or devices (like
  the Xbox 360, for example) can't prompt you to enter a security code
  when you try to sign in.  If you get an incorrect password error with
  an app or device, you'll need to create a unique app password to sign
  in.  Once you've signed in with your app password, you're all set to
  use that app or device.  You'll need to create and sign in with an app
  password once for each app or device that can't prompt you for a
  security code. 

Sign in to your Microsoft account. 
Under Password and security info, tap or click Edit security info. 
If you're prompted for a security code here, enter it and tap or click Submit. 
Under App passwords, tap or click Create a new app password. 
A new app password is generated and appears on your screen. 
Switch to the app or device for which you need the password, and enter the app password displayed on the screen. 

For more info about signing in to specific devices, see App passwords
  and two-step verification.