Help with installing boot grub in Windows 10

I'm having a hard time trying to install on my Windows 10 the Grub bootloader. I downloaded the Ubuntu 18.04.4-desktop-amd64 ISO then ran the Ubuntu live session, then I ran this command sudo fdisk -l

SSD:

According to some internet articles I need to shrink my current SSD at least by 400 MB in order to format a boot partition as EFI FAT32 with a proper flag, and with that I will be able to install GRUB there. I have never used a Linux distro before.

Would someone here give me guidance me with proper commands in order to shrink my current drive which has 223 size, but only has a free space of 33 GIB? I only need a 400 MB boot partition.

Once I have installed Grub, finally I would be able to ran the grub configuration to finally fix the HPET of my motherboard firmware among other things.

With GRUB booting Windows, I can access to the configuration of the motherboard firmware allowed in Asrock, and with that force High Event Precision Timing to Disable Cause in a regular way my motherboard firmware is causing issues with HPET forced enable even if I disabled it, so with the GRUB there is a configuration to force HPET to disable, and force the Windows timer to 3.580 MHz.

GRUB is automatically installed by the Linux installer, Ubiquity, when you install Ubuntu. However, you can use GRUB for Windows only, according to https://www.aioboot.com/en/install-grub2-from-windows/ which provides detailed instructions.

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For the rest of us, here's the sequence to use for installing GRUB by Ubiquity for a dual boot of Windows and Ubuntu:

Download Ubuntu's ISO file at https://ubuntu.com/download

or for a supported 'flavour' with a different Desktop Environment, download from https://ubuntu.com/download/flavours .

Next, check for download errors by https://tutorials.ubuntu.com/tutorial/tutorial-how-to-verify-ubuntu#0

Make a LiveUSB following these instructions on another Linux PC https://tutorials.ubuntu.com/tutorial/tutorial-create-a-usb-stick-on-ubuntu#0

or on a Windows PC https://tutorials.ubuntu.com/tutorial/tutorial-create-a-usb-stick-on-windows#0

Once you make a LiveUSB, install it following these steps https://tutorials.ubuntu.com/tutorial/tutorial-install-ubuntu-desktop#0

and when you get to step 6, Allocate Drive Space
You can choose Something Else to resize the Windows NTFS partition and make room for Linux.

Looking at the picture you provided, there's an EFI partition there already; that's what Windows 10 does by default. Only if your PC had Windows 7 or earlier installed first, would it be partitioned with the Legacy MBR Partition table, which would not have an EFI partition.