Updating ZS570KL International version

[jeitel]

Product Model Name: ASUS ZenFone 3 Deluxe (ZS570KL)
Product Model Number: ASUS_Z016D
Operation System / Firmware or BIOS version : Android 6.0.1     Settings>About>Software information: WW_4.12.40.1781_20170117
CPU 2.34GHz
I have the international version of this phone. I get notifications of updates for the installed applications but nothing at all for the system (firmware and Android). The support I've been able to contact so far has told me that I have the latest firmware available for this particular CPU.
I thought the SKU ( first 2 letters of firmware like WW) was what really mattered.
But a later Android version is what I would really like.

[Christine_ASUS]

Hi jeitel
Thank you for your asking. First of all, I edited your passage and deleted your SN info. Please be aware that sharing the personal information like SN or IMEI on the Internet is quite dangerous. 
Second, please refer to the website. I can only find Version WW-4.12.40.1698 for CPU=2.34GHz.
https://www.asus.com/supportonly/ASUS%20ZenFone%203%20Deluxe%20(ZS570KL)/HelpDesk_BIOS/
Although I can not find other firmware versions for for CPU=2.34GHz on the website, you may try Version WW-5.14.44.1898(For 2.4GHz CPU) with manual update. Yet if there is no pop-up notification after reboot, then the firmware is not compatible to your CPU.
#Update Guide (download the file into the root directory, aka the outermost place, of the internal storage>reboot>tap the "system update" notification)
https://www.asus.com/support/FAQ/1009748/

Furthermore, WW/JP/CN/RU is a big scale of the firmware category based on SKUs or countries, yet some models have their own rule for firmware version due to the device design. For the next time, please check on our official website support page of your model for confirming more information.

[jeitel]

I contacted ASUS technical support via email about this issue. The individual that responded to my inquiry told me that I could install version WW-15.0210.1810.73. I have downloaded it into my phones root directory. After each reboot I now get the pop-up notification "System Update File Detected". I have been informed by ASUS technical support (and others) that I should back up the data on my phone before doing any kind of system update. I have consulted the ASUS online technical support where they direct you to answers for a variety of FAQ's. They present steps to take when backing up to Google drive. I follow this information presented for Android 7.0 and earlier (mine is 6.0.1). Also, there is an app on my phone: "WebStorage" which I believe should allow me to do the same thing on ASUS cloud storage. I have tried both of these methods but have not gotten anywhere with either method. I have contacted ASUS technical support by email for more help. You may have some comments about this. If so, they would be helpful.
Also, I have looked into some software for my Linux desktop PC which will back up phone data directly to PC through USB cable.
Once all of this is done and the firmware is updated, I would be interested in updating my Android 6.0.1 to something newer.