The IDE is at https://account.smartthings.com
However, it is part of the old architecture, and will not give you complete information on anything using the new “edge“ architecture, and beginning next week that’s going to be most zigbee Devices.
Here’s the official announcement:
Hub-Connected Devices Now Use Edge Drivers
Beyond that, even if the device is using the old architecture, smartthings has unfortunately never given us a full network map the way some zigbee hubs do. 
instead, all you will see there is a single snapshot of a single message route that was recorded by the cloud. It’s not necessarily the route most frequently used by that device, or even the route most recently used. It’s just one snapshot in time. At one point it could take 24 hours to update, I don’t know what it does now, particularly with the architecture changes in place.
In the past, some people did add an additional device to the network to get a full Zigbee map by using that device’s utilities, but that’s probably more work than most people want to do. If you want to read about that, the information is here:
FAQ: Mapping your ZigBee network with Digi's XCTU
So regrettably, as far as the original poster’s question goes, there isn’t any way at present with smartthings to see a full network routing table unless you add an additional device.
If the devices are still using the old architecture, you can see some of the routing through the IDE, but not all of it. 
And if you haven’t yet heard about Edge Drivers and the IDE going away, here’s the community FAQ on that:
FAQ: I have no idea what Edge is. Is that a new developer tool? (2022)