Using the Collector app on an iOS device and when I click on the Collector icon it prompts you to use ArcGIS OnLine or Portal for ArcGIS. Normally when you click ArcGIS OnLine it prompts you to enter username and password. On this device it is blank after clicking ArcGIS OnLine.
Device appears to be working fine, can access the web using Safari, etc. Have logged in to ArcGIS organizational account using Safari, etc.