If you want to run the SDL2 version, you currently need to compile SDL2 from source on the Raspberry Pi, to get support for launching full screen applications from the console. The version bundled with Stretch is not compiled with support for the "rpi" driver, so it only works under X11.
Follow these steps to download, compile and install SDL2 from source:
https://github.com/midwan/amiberry/wiki/Compile-SDL2-from-source
With SDL2 installed, you can proceed to install Amiberry as follows:
Install the following packages:
sudo apt-get install libxml2-dev libflac-dev libmpg123-dev libpng-dev libmpeg2-4-dev
Clone this repo:
cd ~
git clone https://github.com/midwan/amiberry
cd amiberry
The default platform is currently "rpi3", so for Raspberry Pi 3 (SDL1) you can just type:
make all
For Raspberry Pi 2 (SDL1):
make all PLATFORM=rpi2
For Raspberry Pi 1/Zero (SDL1):
make all PLATFORM=rpi1
And for the SDL2 versions, you can use the following:
make all PLATFORM=rpi3-sdl2
Or for Raspberry Pi 2 (SDL2):
make all PLATFORM=rpi2-sdl2
Or for Raspberry Pi 1/Zero (SDL2):
make all PLATFORM=rpi1-sdl2
You can check the Makefile for a full list of supported platforms!