Error in opening ebook

hihi, everyone. Some of my clients facing the following error when opening the html ebook. Can nay one help me diagnose what is the problems?

  1. WhatsApp Image 2021-10-17 at 4.32.31 PM

Thank you

It’s one of the security features of HTML Executable: your customer is running a third-party software that you did not allow. See this page: Ebook Content Protection

Thanks for your reply. Will ask the client to check so