When you boot your laptop form the Linux installer, if you cannot see the drive with the unallocated space, that indicates the Linux installer is not for the correct BOS settings on your laptop.
Click your Start Button, then just type msinfo and press Enter.
On the resulting System Information window, check the BIOS Mode section, is that indicated as Legacy BIOS or UEFI BIOS?
You need to download and create a bootable Ubuntu USB installer for the BIOS Mode that is indicated and you should then be able to see the drive when you install Ubuntu.