We have to go: https://www.ingrossoborseonline.com/en/ and click the register button, insert all the details of account and finally click the register button.
We will get an email message from info@ingrossoborseonline.com which tell me to click the link for email verification.
And will show this message and nothing else...
The normal message
| Impostazione | Valore | 
|---|---|
| PHP attivo su | Linux webd014.cluster023.gra.hosting.ovh.net 4.14.66-ovh-vps-grsec-zfs-classid #1 SMP Thu Aug 23 15:15:40 CEST 2018 x86_64 | 
| Database Type | mysql | 
| Versione database | 5.6.39-log | 
| Collation database | latin1_swedish_ci | 
| Collation connessione database | utf8mb4_general_ci | 
| Versione PHP | 7.2.14 | 
| Web Server | Apache | 
| WebServer interfaccia PHP | fpm-fcgi | 
| Versione di Joomla! | Joomla! 3.9.4 Stable [ Amani ] 12-March-2019 15:00 GMT | 
| Versione piattaforma Joomla! | Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT | 
| User Agent | Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.75 Safari/537.36 | 
| Labels | 
                                        Added: 
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 | 
    ||
| Status | New | ⇒ | Closed | 
| Closed_Date | 0000-00-00 00:00:00 | ⇒ | 2019-03-30 12:39:58 | 
| Closed_By | ⇒ | franz-wohlkoenig | 
| Status | New | ⇒ | Closed | 
| Closed_Date | 0000-00-00 00:00:00 | ⇒ | 2019-03-30 12:39:58 | 
| Closed_By | ⇒ | joomla-cms-bot | 
Closed for Reasons stated above (Forum).
Set to "closed" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/24419
Please ask in a forum for help and close your issue here on GitHub. The issue that you describe isn't a Joomla core issue. You're using JoomShopping and an AJAX-driven registration form that is not part of Joomla core.
I can't reproduce your issue with a "normal" Joomla.