4.15 install instructions, Error 1 & 2

Hi folks, two related things:

1. Would it be possible to edit the INSTALL doc to provide a bit more info about how one should best install Thunar? Feasibly including git clone (if that's correct), and where to get the latest (4.15) (gitlab) versions of various packages? Thanks.

2. Having done:

git clone https://gitlab.xfce.org/xfce/thunar.git
./autogen.sh
sudo apt install xfce4-dev-tools
sudo apt install gtk-doc-tools
sudo apt install exo-utils
sudo apt install libexo-2-dev
git clone installed libxfce4util libxfce4ui
./autogen.sh
make

I'm getting Error 1 & 2 and can't continue. Pastebin here. Any help appreciated - cheers!

Simon