To download your .mobileprovision file, navigate to the Apple Developer portal, then sign in to the Member Center.
Within the Member Center, click the Certificates, Identifiers & Profiles link.
Under the iOS Apps heading, click the Provisioning Profiles link.
Your Distribution Provisioning Profile should be visible in the list.
If you do not see a Provisioning Profile, ensure that you have followed the correct procedures for creating an Ad Hoc Provisioning Profile and/or an App Store Provisioning Profile.
Select your Provisioning Profile, check it is the correct type, and click the Download Button.
Your .mobileprovision file will be downloaded to your computer.