I have saw that another person have the same issue as me in the past but I dont fint the right channeI to conect T-Mobile over the web.
I have enrolled for a prepaid account using T-Mobile eSim app. All the process worked fine (I got a new phone number and had my Credit Card charged) but in the end there was some error in the app and the new eSim profile was not installed on my iPhone. I am locked out of service, since the app requires a different e-mail and the creation of a new account to run again, the app is only for buying and is expected that no error occours during the process.
I need that T-Mobile sends me the QR code for the eSIM so this way I will be able to install the eSIM on my phone.
Best answer by tmo_chris