"The Connection for This Site is Not Secure"

I was browsing on Microsoft edge when I found something very cool that I wanted to download. I researched it online to make sure it wasn't a virus that would steal my information and clicked on the download button. Though instead of starting to download this app, it brought me to a screen that said, "the connection to this site is not secure" and below it read that the page "sent an invalid response". I had already confirmed that this wasn't a virus but the videos I had watched informed me that my antivirus might think it was one and shut it down completely. So, I went into my settings and disabled both the firewall and auto protect for my antivirus (Norton 360). After shutting down my antivirus I went back to the download page and clicked download. Same page popped up. I tried refreshing the page, but nothing changed. I tried looking up articles about people having the same issues as me on YouTube and other websites, but nothing seemed to work. Does anyone have a solution to this issue?