Archives don't contain submodules

[SoapSpangledGames]

I downloaded the latest zip file, and typed make at the command line. This is what I got:

$ make
make -C uSockets;
for FILE in Broadcast HelloWorld ServerName EchoServer BroadcastingEchoServer UpgradeSync UpgradeAsync; do g++ -flto -O3 -lpthread -Wpedantic -Wall -Wextra -Wsign-conversion -Wconversion -std=c++2a -Isrc -IuSockets/src examples/$FILE.cpp -o $FILE uSockets/.o -lz & done;
for FILE in HelloWorldThreaded EchoServerThreaded; do g++ -pthread -flto -O3 -lpthread -Wpedantic -Wall -Wextra -Wsign-conversion -Wconversion -std=c++2a -Isrc -IuSockets/src examples/$FILE.cpp -o $FILE uSockets/.o -lz & done;
wait
make[1]: Entering directory uWebSockets-master/uSockets'
make[1]: *** No targets specified and no makefile found. Stop.
make[1]: Leaving directory 'uWebSockets-master/uSockets'
g++: error: uSockets/.o: No such file or directory
g++: error: uSockets/.o: No such file or directory
g++: error: uSockets/.o: No such file or directory
g++: error: uSockets/.o: No such file or directory
g++: error: uSockets/.o: No such file or directory
g++: error: uSockets/.o: No such file or directory
g++: error: uSockets/.o: No such file or directory
g++: error: uSockets/.o: No such file or directory
g++: error: uSockets/*.o: No such file or directory
$

Any suggestions on what's happening, and how to fix it?

GitHub don't pack submodules in generated archives