A quick solution is to install some kind of "open link through" application, such as https://play.google.com/store/apps/details?id=com.tasomaniac.openwith&hl=en_AU&gl=USThen
After successful authorization, when the Intel map opens, click "Share", select "Open link with", then select IITC Mobile.
Unfortunately, in Chrome it is not possible to open the link immediately in apps.
And to determine the problem why the browser opens, do this:
1. In the advanced settings, turn on the Debug item
2. Try to log in
3. When the transition to Chrome happens, go back to IITC Mobile
4. Tap Debug and send here a screenshot. It should say something like "no ingress intel link, start external app to load url: ..."