[Upgrading, Modifying and Unlocking] albyhf:
Thanks to KimLe who made me understand where I was wrong

So here my tutorial step by step.

Necessary: A Windows 10 (or 7) PC, internet connection, USB cable

FIRST WARNING:

I won’t be responsible for any kind of error or damage that occurs to your tablet during or after following this guide or flashing any file. You should know what you’re doing.

Take a full backup at first and proceed at your own risk!

Pay attention: ALL DATA WILL BE ERASED FOLLOWING THIS TUTORIAL! For TWO times (this one was the second warning)

- First of all download and install the the last MTK usb drivers on your windows PC: https://androidmtk.com/download-mtk-usb-all-drivers

- Download "ADB and FASTBOOT tools" on your PC: https://droidfilehost.com/download/downl...r-windows/

and decompress it in a Windows folder. For example in a Desktop folder called "ADB and FASTBOOT tools"

HOW TO UNLOCK THE BOOTLOADER (all data will be erased):

- USB debugging procedure:

turn on your tablet, go to Settings -> About phone -> Now tap on the Build Number 7-8 Times until you see a message “You are now a developer!“.

Then go back to Settings -> System -> Advanced -> Developer options.

Go down to "DEBUGGING" and enable USB debugging. (be sure, when you connect the tablet to the pc, to allow USB debugging when the tablet asks that, and to select "Always allow from this computer".

- with the tablet on, connect it to your Windows PC with a USB cable (be sure the USB debugging is allowed, then).

Open the "ADB and FASTBOOT tools" folder on the PC and open a command prompt window in it, preferably typing "cmd" in the Explorer Address Bar. I know there are other ways to open a Command Prompt, but some of them didn't work for me. So I think this is the best one.

Here how to open a Command Prompt this way: https://lifehacker.com/quickly-open-a-co...er-5989434

- In the Command Prompt you have opened, type and confirm: adb devices

If on the Command Prompt then compares: "List of devices attached" and then a number, it's ok. If not, there is a problem (android USB drivers, usb debugging not allowed, etc.)

- Then type and confirm: adb reboot bootloader

Now your tablet reboots into fastboot mode (wait some seconds)

- Then type and confirm: fastboot devices

If on the Command Prompt compares a number and the "fastboot" writing....you are ok. If not, there is a problem with USB drivers, probably. Search and install android drivers, check that in device manager there aren't yellow triangles etc.

- Then type and confirm: fastboot flashing unlock

Then the tablet will ask you to confirm the decision pressing for example the "Volume Up"

- The booltoader should be unlocked. You can check it typing and confirming in the Command Prompt: fastboot getvar unlocked

If the answer is yes, the bootloader is unlocked.

- Type and confirm in the Command Prompt: fastboot reboot

Your Android device will now reboot and during this, alla data will be erased.

ACTUAL ROOTING, with unlocked bootloader (all data will be erased again):

- Download the Stock Rom of your device from internet (iPlay 30 got the same firmware of iPlar30 pro)

https://www.alldocube.com/en/category/firmware/

- put the decompressed Stock ROM files in the same folder of "ADB and FASTBOOT tools"

- Attach your tablet via USB cable to the PC, copy the "boot.img" file you can find now in the folder of "ADB and Fastboot tools" and paste it in the tablet storage.

- Repeat the "enable USB debugging" procedure on the tablet

- Install the last Magisk Manager Apk on the tablet: https://magiskmanager.com/downloading-magisk-manager/

- Open on the tablet, the installed Magisk app: you will find "Magisk" and "Manager". Go to Magisk, then "Install", then "Select and Patch a File". So select the "boot.img" file you put in the tablet storage before.

The app will patch it and will create (usually in the Download folder of the device) a new file, called something like: "magisk_patched_XYZ.img" (where XYZ could be any number or letter).

Copy that file in the "ADB and Fastboot tools" folder of the PC (don't delete any file in that folder, just copy the new patched file from the tablet and paste it in that PC folder).

- With the tablet connected to the PC, then open a Command Prompt in the "ADB and FASTBOOT tools" folder

- Type and confirm: adb reboot bootloader

- Type and confirm: fastboot --disable-verity --disable-verification flash boot magisk_patched_XYZ.img

PAY ATTENTION: I wrote XYZ, but you have to put the name of your Magisk patched file.

The command must match with the name of your specific patched boot image file you copied from the tablet

and pasted to the PC folder.

- Type and confirm: fastboot --disable-verity --disable-verification flash vbmeta vbmeta.img

- Type and confirm: fastboot reboot

- Your tablet will reboot again with all data erased. (but the tablet is not rooted yet)

- Set up the tablet. Download and install again Magisk on it. Run Magisk. It will download automatically the necessary for the ending procedure and then it will do automatically a reboot of the tablet.

THEN ROOT IS DONE!!!!