Apple Search Ads Conversions include taps on the install button in the App Store
after a tap on an Apple Search Ad. The conversion window is an install that occurs
within 30 days of tapping the Search Ad. Redownloads are included as new conversions.
Apple Search Ad Conversions include users with Limt Ad Tracking on.
Redownloads may or may not be counted as a new attribution. Kitemetrics attribution window is 30 days after the user taps on the Search Ad.
The descrepency between Apple Search Ads Conversions and Kitemetrics attributions may be around 20%. This is manily due to users with Limit Ad Tracking on and a small percentage is due to users that install an app but either cancel the download early, never open the app, or uninstall the app prior to opening it.
Due to a bug with iOS 11.3.0 - 11.4.0 Apple Search Ads did not report Attributions for installs for users running those versions of iOS. iOS 11.3.0 was released on June 5, 2018. The bug was fixed in iOS 11.4.1 on July 9, 2018.
As a result of this bug in iOS 11.3.0 - 11.4.0 Kitemetrics was unable to report Attributions for installs made by users runnning the affected versions. As users begin to upgrade to iOS 11.4.1 and higher, attributions will return to normal.
Apple Search Ads - Mobile Measurement Partners