Although ArcGIS Collector has been removed from the Google Play store, the APK file can still be downloaded for sideloading on a device. See the link below.https://appsforms.esri.com/products/download/index.cfm#ArcGIS_Collector
hi, I know an app store called null48 maybe you can find it there here a link https://null48.net/
btw i took a look at that site but I didn't find the apk version??