The GPT format is correct for a UEFI install. But you must set BIOS to be in UEFI mode & also boot to the installation media using the UEFI option.
(1) Go into BIOS Settings & set it for UEFI mode (instead of Legacy). Turn off CMS (if present) & turn on Secure Boot. Remember to save changes as you exit.
(2) Use the BIOS Boot menu to boot to the Win 10 media as a UEFI device which means to choose the UEFI option to boot it. You need to press an F-key during boot to get to the BIOS Boot Menu. If you don't know it...
Get access to BIOS settings & Boot Menu: F-keys/Hotkeys by System Manufacturer (OEM)
Note: That is an informative 3rd-party site. But I know nothing (bad or good) of any downloads or links that are there.
(a) Plug in the USB Installation media.
(b) Bootor reboot the computer.
(c) Press & hold the F-key at the manufacturer's logo (or at the black screen just before the logo).
If the key was pressed in time, mine shows activity at the bottom of the screen,
& the BIOS Boot menu soon shows up.
(d) From the BIOS Boot Menu, choose the "UEFI" option for the media, if offered.
Mine names the device brand & precedes it with "UEFI:".
That should do it. Good luck.