Just an FYI, ATT ActiveArmor Mobile Security on my iPhone through ATT Wireless is blocking previewer.adalo.com. It is stating it is blocking Malicious Traffic. “ActiveArmor suspects that this link could be an attempt to steal your information or install malware.” This is a stopping event and you cannot preview apps at all.
I think this has happened before with other services. If you submit a support ticket Adalo can contact ATT and remove the warning.
Thanks I just submitted a report.