It's always funny to demonstrate how systems can be stupid.

1. Open "Developer Tools" (Ctrl + Shift + I on Chrome)

2. Go to the network section

3. Start the test

4. Search for a request having the url starting with https://zte.zanichelli.it/viewer-be/api/homework/zte_ and click on it

5. Open the Response tab

6. Copy the content of the response in sources

7. Run the command below, by default it won't show the questions, but only answers. Use questions to change this.

   php main.php [questions]
   

8. Enjoy your mark :P

You can find all the methods in the class file zanichelli.php, they are well documented and also simple to understand by reading the code, because the Zanichelli security sucks.
Have a great time reading infos (also emails of the creators) and passing all the tests with maximum marks.
For Zanichelli, base64 doesn't protect you.

Dametto Luca
ShiSHcat