"Roma dixit" challenge

 Our mission:

Dear students, we have just received a letter from Professor Minerva McGonagall addressed to the participants of the Roma dixit project, which was brought by an owl!!!

When we opened the manuscript we found that it was encrypted with the Caesar cipher.

We assume that it is a very important message and that the teacher encrypted it as a means of protection in case it fell into the hands of the evil Lord Voldemort.

To decrypt Professor Minerva McGonagall's letter, each international group will have to discover a numerical code by answering some questions on a Google form.

Are you ready for the challenge?