Dual Boot Dell Inspiron 7577 Windows SSD and Linux HDD

I just finally bought a laptop and I am motivated to learn working on linux. The laptop is a Dell Inspiron 7577 that came with two hard disks: - C: PCIe NVMe M.2 SSD 256GB on which is installed windows 10 - D: HDD 1000GB "Healthy (Primary Partition)" My idea is to install Ubuntu on a partition of disk D: HDD 1000 GB and use it in dual boot with windows 10. 1) I shrunk the volume D: into two equal sized partitions because I want to install ubuntu 16.04 on the Unallocated partition of HDD D: 2) Then, I downloaded the .iso of Ubuntu and booted it on my usb pen drive using rufus. 3) Restarted the computer and run the ubuntu installer 4) In the page where it is supposed to ask - according to the tutorial enter link description here - whether to erase the computer, install alongside windows and other options, the page is different and do not allow me to select anything. Any suggestion?