In order for app retargeting to work, the program must have a URL scheme configured correctly for actual links. For example, the Instagram profile link opens the profile screen in the Instagram program. Another example is sales or merits for app users – after they click the link, they should get to the proper page of the program, not just the foremost page which could be confusing. At an identical time, if the user doesn’t have an app mounted on their phone yet, they may be redirected to App Store or Play Store after which get to the proper page after the installing.
Although these particulars should be rigorously managed, deep links can give a good user event if used as it should be.