Compiling requires the haxe toolkit to be installed, in order to compile KubeJS scripts and modpacktools to build the modpack.
Run these commands
# (only required on first build) install kubejs-haxe bindings
haxelib install kubejs
# build haxe scripts
./buildhaxe.sh
# use modpacktools to compile modpack
mpt buildtwitch
exports can be found in build