OTA means Over The Air. We can't give you an OTA link cos ASUS will push that update to you under your System Settings -> About Phone -> System Update.
That being said, I think the link you're looking for is: http://support.asus.com/download.aspx?SLanguage=en&p=29&s=1&m=PadFone+Infinity&os=&hashedid=86Xopn8p76rO9oNf Click on Android.
Download this file. Unzip it. There will be another .zip file in it. Don't unzip the second one. Put it at the root of your phone's internal memory. Phone will recognize the update and will ask if you want to do it.
Also don't forget that if you are coming from 4.1 (which you are) this update will delete everything from your phone, so make a backup.
And if you were planning on unlocking the bootloader, unlock it before updating, because you can't unlock it anymore on 4.4.
Did you download it from the phone? Because you need (it's important) to download it from a computer and put it in the phone via USB. It won't recognize it if you download it from the phone.
Also if still not recognized, either download TW version or unlock bootloader, install a custom recovery and install the update with that.
WW_PFI_user_11_8_10_38_UpdateLauncher Brings Battery,recent applications,Autobrightness & some performance issue Bugs. in previous updates sound is getting very high but now after update to latest version it's gone WTF happening ??
Many thanks for you trying to help me. I entered the link and searched for my update and didn't find it. I am new to android and don't want to make a mistake by updating with the wrong patch.
I would be grateful to anyone who could give me the right download link.