Hi Wimpy, quick report.
I am french and french keyboard configuration don't work on setup wizard. No language or keyboard layout are avaiable.
It is all blank but next button works so I installed it with english keymap I change layout after setup wizard.
In the welcome panel in raspberry pi section you put a link on pepperflash to :
https://ubuntu-mate.community/t/rpi2-tutorial-ubuntu-mate-15-10-install-flash-player-quick-version/2739
But the link is not good (page not found).
I did a better tutorial for pepperflash too, this one was the first version the newer (and best one) is :
I think you should change the link 
I just install it I will made more reports if I found something more 
Aworan