Non tech lady has multiple older Android devices pre Android 6 requires Norton security. Currently had Norton Premium but no longer compatible.
Unfortunately, you are going to have to research other security options. There is no Norton product that will install on pre Android 6 devices. If you already have Norton Mobile Security installed, it does seem to continue to work. I have one device on Android 5 that still functions as it always had. Just will not be able to upgrade to the latest versions of the product.