I will show you how I root and install custom ROM LineageOS 14.1 on the Samsung Galaxy Tab Pro 10.1 WiFi SM-T520. This tablet was on the original stock firmware 4.4.2 KitKat and is not scheduled for any future upgrades from Samsung. It is notoriously slow and laggy on the stock software. This newer version is Android 7.1 Nougat, and it makes the Samsung Galaxy Tab Pro 10.1 run much faster and smoother.
You can do this yourself if you are comfortable or contact the android experts at iQ Android to take care of this for you.
We guarantee our service 100%. See links below for the files to do this. You can reach me on XDA Developers username: iqcomputers.
TWRP 3.1.1 Custom Recovery