Go to your device Settings > Security (or Apps) and toggle on Install Unknown Apps for your file manager or browser.
Version was released during a transitional period for Android (roughly 2013-2014). It predates the “Chromium-based” redesign of later versions but offers a more polished interface than the even older Java-based versions. opera mini 7.5.1 on android.apk
Even a legendary browser can have quirks on modern Android. Go to your device Settings > Security (or