Hey Pedro,
I have responded to your query in the Target community but to answer it here as well.
For supplemental data id, you can look at the analytics network call in Omnibug or network panel for the sdid parameter like below:

This value, should match your target delivery call supplemental data id(search for 'delivery' in network panel). Look at the below supplemental data id, it matches the above analytics call for A4T setup to work correctly.

For tracking server, look at the request url under headers in the same network call, the domain is your tracking server.

Hope the above helps.
Cheers,
Abhinav