The link you sent is not exactly suitable for Zynthian (I’ve made the same mistake when I was configuring my screen). Try keeping the same connection as described in your link, but reconnect BL from pin 12 to pin 32(gpio-12). Then you can try compiling the dtoverlay (something like a driver) from the topic @le51 referenced. First grab the source file. ssh into your pi, execute command nano mytft.dts this will open text editor, paste the contents of the file you grabbed and press ctrl + O (save) and then ctrl + X (exit). Now you can compile your dtoverlay using following command
sudo dtc -@ -I dts -O dtb -o /boot/overlays/mytft.dtbo mytft.dts
Then go to webconf, and set up the screen as shown in this post.