To start using App in the Air for Business, you'll need to create an account (if you haven't created one before) or sign in (learn more here).
Open your Profile - Settings.
Tap on the "Connect account" (Android), and select "Business account" in the list. Then click on "Sign up".
Then select "Create account" and create it.
The ability to switch between the business account and the personal account will appear in the app.
NOTE: If you already have the app, the current account does not go anywhere. A business login (App in the Air for Business)is an additional authorization method that exposes all the app's business functions (including travel policy for flights and corporate card payment).