A coordinate system is at play at:
- The GPS
- The Web Map (set by the basemap)
- The service (set at publish)
- (sometimes) the source data, when working with referenced ArcGIS Server services
There are up to 3 transformations that can occur:
- DT1: GPS Receiver to Web Map (using location location profiles on device)
- DT2: Web Map to Layer (using default or service defined datumTransformation)
- DT3: Layer to geodatabase (for ArcGIS Server services where the source data is different to the services coordinate system)
https://youtu.be/7AuACl8PYKU?t=772
You should:
- Try have the same coordinate system across the board, to make life easier
- Ensure that the desired datum transformation occurs at each stage and are supported
- Be aware of the behaviour of DT2
- Be aware of the behaviour of when publishing a service i.e. does it reproject on publish, do custom datumTransformations get created etc
So for you you ideally want:
- NAD83 CSRS UTM Zone 20N GPS
- NAD83 CSRS UTM Zone 20N basemap in map
- NAD83 CSRS UTM Zone 20N service
Or if oyu don't have a custom basemap service:
- NAD83 CSRS UTM Zone 20N GPS + location profile to datumTransformation to WGS84
- WGS 84 basemap
- NAD83 CSRS UTM Zone 20N service, with no (default) or chosen datumTransformation at a service level.
For DT2 How can I control how hosted feature layers are reprojected when viewed on ArcGIS Online basemaps?
https://doc.arcgis.com/en/arcgis-online/reference/faq.htm#anchor69
Also, ArcGIS Collector is retired. You should be on ArcGIS Field Maps.