Anytime or any time

Sometimes I get confused when to use “anytime” and when to use “any time”. Would you please tell me when I should use “anytime” and “any time”. Thank you.

Anytime is an adverb meaning at any time whatever, at a time which is not or does not need to be decided or agreed: Call round to see me anytime.
US We don’t expect the economic situation to change anytime soon.

You can say either ‘anytime’ or ‘at any time’.