The rom is not much stable and I don’t suggest you to use it as a daily driver you can download unofficial cm13 for Xperia Z from the download link from below download section.For updated bug report refer to Xda thread here.
See also: List of device got Official CM13 ROM
Before starting make sure you are ok with the bugs of cm13 for Xperia Z.For installing cm13 or any custom rom in your device make sure you have installed any custom recovery installed in your device I recommend you to install TWRP recovery in your device.
So after completing above requirement’s let’s start the step by step guide on How to install Cm 13 in Xperia Z and update it to android Marshmallow 6.0.
#How to install Cyanogenmod 13 Rom on Xperia Z
1.Download official CM13 Rom for Xperia z and the appropriate Gapps 6.0 package from a link given below Copy it in your in your device.
2.Now place the Cyanogenmod 13 rom and gapps 6.0 zip file in sd card.
3.Now reboot to Recovery mode and flash Android marshmallow rom in your device.
4.Then flash CM13 android marshmallow rom and gapps from the recovery in it.
5.Now Clear cache and Clear Data from twrp recovery.
6.Reboot your device.Done! you just flash cyanogenmod 13 rom in your Sony Xperia z.