[Miscellaneous Android Development] martyfender:
First of all adb and fastboot binaries need to be installed on your pc and the Intel drivers installed and setup properly. I usually copy the Ares8A_recovery_twrp.img to the adb/fastboot folder on the pc.

Developer options and USB debugging need to be enabled on the tablet. In developer options on the tablet check OEM unlocking.

Decide which root solution you will use, either Magisk or SuperSu. I highly recommend Magisk as SuperSu is no longer developed. Copy, don't unzip, either the Magisk.zip or the SuperSu.zip to either your tablets external sd card or the internal sd.

Reboot the tablet into bootloader/fastboot mode. From the pc's adb/fastboot folder, shift, right click on an empty space to open a command prompt here. In the command window issue fastboot device and hit enter and you should see your device fastboot serial number listed if it is connected to the tablet properly. If the above is working:

Temp boot twrp by issuing this in the fastboot prompt:

fastboot boot Ares8A_recovery_twrp.img

Hit the enter key and the device should temp boot to TWRP. I go to settings and set the date and time and language. Since it is only temp booted, these settings will have to be redone when you flash twrp permanently, later.

Backup your device, boot.img, system and original recovery in twrp first, see the op instructions. Choose the factory reset option in twrp. Do not reboot, you must now flash Magisk or SuperSu first to patch the boot.img. Confirm in the twrp window that it successfully flashed and patched the boot.img. If you get an error, then something went wrong. If you never flashed root before, the message should state that the stock boot.img is detected.

Follow my updated instructions in the Op to flash Magisk.zip or SuperSu.zip

If you are using SuperSu, be sure to use the latest beta systemless version and not my unofficial system mode version. Reboot, first boot after factory reset can take some time, up to several minutes to recreate the unencrypted data partition. The device will appear to be in a boot loop. Setup Andriod once it boot to the setup screen and confirm that the Magisk Manager was also installed in apps. if not, you will need to download and install it separately.

Follow my updated instructions in the Op to flash Magisk.zip or SuperSu.zip

Links for installation instructions are on the above page.

I also recommend that you flash TWRP to your device replacing the stock recovery.

While booted into bootloader/fastboot mode on the tablet issue in the command prompt from the pc:

fastboot flash recovery Ares8A_recovery_twrp.img

hit enter and read the message to confirm that it was successful.

Things to have on the internal SD of your tablet the stock backed up boot.img.

copy. In other words, copy the boot.emmc.win from the twrp backup folder to your downloads folder and rename it boot.img. Second, the Magisk.zip and Magisk Manager.apk and finally the latest TWRP flashable Magisk Uninstaller.zip. I have had the external SD reader fail on 4 out of the five devices I own, so I keep the stock, backed up version in the TWRP folder on internal, deleting the stock recovery backup, recovery.emmc.win, in it so I don't again accidentally overwrite twrp by mistake if I ever want to restore the stock system. The stock system should not contain the original data partition either, as it was encrypted.

When I update to a new version of Magisk, I never use the direct install method as it has caused many issues. I instead choose download zip only, reboot to twrp and install the zip from there.

Again I recommend reading the info in the OP (Opening Page), especially the updated info.

UPDATE: I now use the The Magisk module: Busybox for Android NDK as it has a much newer version of busybox in it.

If you plan on using Adaway, go into Magisk Manager settings and click on systemless hosts, you should then see a confirmation toast. Now reboot for the module to be enabled, just like any other module installed. Make sure systemless hosts is enabled in Adaway, also. It should be on by default.

The above instructions assume you are on a Windows PC. If you are on Linux, you must use sudo before the fastboot commands to run as root. That may be true with a Mac, also, but I am not sure, as I used to work on Macs, but have never connected Android devices to any.