GRUB2 package failed to install on dual boot with windows 10

Hello, I have problem on GRUB2 package installations when I install ubuntu as dual boot with windows 10. My BIOS is LEGACY and I already created 2 partitions, one is ext4 and one is swap. When GRUB2 pakcage installation running it give error which said GRUB2 package failed to install. I already read any suggestions but I still didn't understand. Some people said that I must create one partition again to install bootloader. My questions is: Is that true that I must create one partition again as bootloader partition and how to create that ?

Thank you.