Add iPhone 8 to my Trend Micro Maximum Security account

  I received my uncle's iPhone 8 after his passing. I'm trying to add it to my existing Trend Micro Maximum Security account. I tried scanning the QR code. That sent me to a screen that had an icon in the center with concentric circles. The circles had little images in them. There is also an arrow in the upper right that swoops up and to the right. None of these images seems to be clickable. The arrow appears to point to a symbol that provides a download function. When I click it, it gives me a message that says "File Manager Required" and gives me an options to Cancel or Download. I have downloaded the File Manager app a couple of times, but still cannot run the download for TM Maximum Security. Every time I try, I get the same message about downloading the File Manager app.

  So, then, I tried sending an e-mail. I opened the e-mail in my iPhone and clicked the link. It took me to the same screen as the scan.

  I tried downloading it from the App Store, but can't find Maximum Security there.

  Am I missing something. Can this iPhone be added to my account?