Official firmware for Moto G 2014 XT1069
To obtain original firmware -Sign in on Motorola / Lenovo (Motorola had been taken over by Lenovo) site with device details , creating an account and search for firmware


Edit: OP has confirmed that he is unable to locate on the Motorola forums as older devices firmware is apparently removed. It is suggested that he mail the OEM or in the OEM forums for sha / md5 of the firmware and compare with that of XDA download as explained here Is there a way to verify stock ROMs?


XDA firmwares are generally legitimate, but best of course is to get it from OEM if you don't trust


Firmware is usually downloaded by folks and hosted on file sharing sites like Mega, since 



a) They can't or may not be permitted to link to original source always

b) Firmware may not be available on original source as later versions may replace earlier OS versions

c) For easier sharing - practically all sites hosting firmware use such sites

Since you specifically drew attention that you are new to this, downloading correct firmware is the first step and following instructions given by OEM / sites like XDA meticulously