Thanks for this nice message. Note that the research I discuss in this blog is not done by me. Here, I am only a participant like anyone from Hive.

How can I join Hivefest7 please? Is it online?

This year, HiveFest7 will be in person. See here for more information.

and i guess that the website of participation in the study are not working for the moment! Maybe not allowed in all countries?

I have just checked and it fully works. You can also contact them by e-mail if needed (blockchain-study@socialmedialab.ca).