The Install Date in Appsflyer is attributed to the Funnel native Date dimension and have the same behaviour like the Overview Page in the AppsFlyer UI. We will attribute new events to installs made 2 years back in time (by reloading the last 2 years of data every day). These reports includes both paid and organic data. 

When connecting you have to select if you want the first time installs (and re-installs outside of attribution window) or retargeting attributions. The first option will populate the installs metric. The latter will give you a Conversion Type dimension that is either re-attribution (re-install within attribution window) or re-engagement (user already has app installed but gets reactivated), these will be counted in the Conversions metric.

These dimensions will only be available if "detailed dimensions from Facebook" is selected when connecting a data source in Funnel.

*These metrics are marked as non-aggregatable, this will lead to the metrics totals not being shown and will force you to look at all dimensions at once in the Data Explorer. The case that causes this is when the user uninstalled the app and then reinstalled after the reattribution window (default 3 months). In these cases the user will be counted on both install dates. This might not lead to any significant discrepancy and if so it's possible to create a custom metric copying the value of the metric (thus making it aggregatable again).

SkadNetwork is a new type of direct install attribution that was introduced by Apple in iOS.14 and above.

**These are generated for each custom event available from your app and derived using Null Conversion Value.

The dimensions in the aggregated reports are limited to a certain number of unique dimension values per day. If you exceed that limit all other dimension values will be group under one collective dimension value. This is the same behaviour that can be seen in the Overview page in the AppsFlyer UI.
Read more about it here.