I realise this is a necropost, but I only just saw this thread. For reference...
The e-CAS tracker doesn't have any magical powers to access e-CAS, and (like robsluv said) just works with the info you give it. However, it does do a couple of "clever" things you might not think to do. This only applies if you can't access e-CAS when you sign up for the tracker (if you can access it already, it simply uses the details that are already known to be working).
The main one (which is what causes the most problems for people) is that it tries alternatives for your surname. E.g. if you put in two names in the surname field, say "Smith Phillips" it tries:
1) Smith Phillips
2) Smith
3) Phillips
It's surprising how many people misread the instructions, and put their full name in, which is part of the reason I started making it do that. Occasionally though, there are people with multiple last names, or hyphenated last names, where only one last name actually works in e-CAS.
Second, if there is any potential ambiguity for your country of birth, it tries all of the possibilities - e.g. UK, England, Scotland, Wales. Normally when people check e-CAS manually to see if it works, they just put in their "correct" country of birth. UK almost never works, England usually does (even for people born in Scotland).
For some people it tries 8 or 10 different combinations of surnames, countries, and login ID's.
Now, when it emails you it does say which combination is the one that's actually working, so there shouldn't be a situation where the tracker can access e-CAS but someone doesn't know themselves what info to put in to access e-CAS manually. If there's ever confusion though, my contact info is very easily accessible from the website.
Matthew