Hi
qasimali284Thank you for your asking.
Kindly provide me your current firmware version: Settings>System>About Phone>Software information
Please note that the system update can primarily be update to the next version of your current version, e,g. WW-16.0610.1908.83>WW-16.0610.1911.89.
Basically, you just download the OTA file on ASUS website to the root directory, aka the outermost place, of the internal storage. Re-boot your phone, and tap the system update notification.
#Manual Update Guide
https://www.asus.com/support/faq/1009748If you still can not perform manual update successfully, please provide me a video of your updating process for further checking.