WhatsApp for Samsung I9070 Galaxy S Advance

The S Advance runs Android 2.3.6 to 4.1.2, and Google's modern login servers often reject these old clients because their root certificates and TLS support are outdated. First check that the date and time are correct under Settings > Date & time (a wrong clock breaks the secure handshake), then try Settings > Accounts and sync > Add account > Google > Existing. If it still loops, update Google Play services if any update is offered, or sign in to the account once in a desktop browser and approve the new device. On the oldest builds the account may simply refuse to authenticate, in which case the phone has to be used offline with apps sideloaded as APKs. See how others solved this on Reddit

On Android 4.x devices like the S Advance, go to Settings > Accounts and sync > Add account > Google, choose Existing, and enter your credentials. Make sure the date and time are correct under Settings > Date & time first, since a wrong clock breaks the secure connection, and apply any pending Google Play services update. Because Google has retired support for these old login clients, sign-in can still fail outright, and if it does the account cannot be added on this OS. See how others solved this on Reddit

This happens when a browser is set as the default handler for web links. Go to Settings > Applications (Application manager), tap the browser that keeps grabbing links, and tap Clear defaults. Open the link again and, when the chooser appears, pick the app you want and tap Always. For an app that should claim its own links, open that app and look for a default or supported-links option in its settings. See how others solved this on Reddit

Note that Chrome's last versions for Android 4.1 are very old, but if you have it installed: there is no Default apps menu on Android 4.x, so the way to switch is to clear the current browser's defaults under Settings > Applications (Application manager) > the browser > Clear defaults. Then tap any web link, and when the chooser pops up select Chrome and tap Always so it becomes the default going forward. See how others solved this on Reddit

Largely yes. The S Advance shipped with Android 2.3.6 and topped out at 4.1.2 Jelly Bean, which is over a decade old and gets no security or Google service updates. Most current apps and even Google sign-in no longer work, so it is best used as an offline or single-purpose device for music, photos, alarms, or a media player. A lightweight custom ROM for the i9070 can stretch its life a little, but mainstream apps will stay unsupported. See how others solved this on Reddit

On the S Advance's Android 4.1.2, Developer options are visible directly, so go to Settings > Developer options and toggle on USB debugging. (On Android 4.2 and newer, where the menu is hidden, you would tap Build number seven times under Settings > About phone to unlock it, but the S Advance does not need this.) Then connect over USB and accept the debugging prompt on the phone so ADB can talk to it. See how others solved this on Reddit