My Apple ID was locked for security reasons. How do I unlock it?

I created a new Apple ID for my wife's Mac mini so she could have her own icloud email. It worked for a couple of days and then quit. When I tried to sign back in to the Apple ID it gave an error message: This Mac can't connect to iCloud because of a problem with "[Apple ID username]" Open Apple ID preferences to fix this problem.

When I go to preferences it says: You can't sign I because your account was disabled for security reasons. To enable your account, reset your password at https://iforgot.apple.com.

But, when I go to that site and enter my new Apple ID it says "This Apple ID is not active."

How do I get my new Apple ID unlocked?

Thanks for any help!