It seems that the Email was not arriving because the account already had a personal Evernote account.
It seems like if an Email address is linked to a personal Evernote account, it cannot receive Evernote Teams invitations (which is a bit weird...).
This is still strange, as we were unable to close the personal account associated with this address. When we clicked on the "send confirmation code" button, the confirmation code never arrived either.
The solution was to send the invitation to another address.
Here is the solution I found to contact the support:
I used this link:
https://help.evernote.com/hc/en-us/requests/new?ticket_form_id=254668&guest=true&guest=true
(Thank you @PinkElephant).
I chose:
1. Account Management
2. Two-Step verification
3. This allows to click on "Submit ticket".
