Here is the mistake - extended partitions is what I expect to see in MBR based partitions and not GPT which would require the EFI partition. The guide is given for UEFI/GPT installs.
If your Windows is installed in BIOS/MBR scheme you need to install Manjaro in the same way. This is not difficult but different. You need space for / (and evtl. swap & home) partition and install the grub's 1st.instance in the MBR. All is supported from the installation GUI.
I'm quite new to Linux. Could you please link to a guide for dual booting XFCE on my computer. My hard disk structure: 1 Windows 10 Partition (PRIMARY), 1 Windows System Reserved Partition (PRIMARY), 2 partitions containing my data (LOGICAL)