You will need a $1.99 subscription to CrowdGrader (valid for the entire class) in order to submit homework.
Click on Build > Clean Project in Android Studio.
Zip the whole project directory (the directory containing the app folder, not the app folder itself). If you use the command line, you can go to the parent directory of your project directory (I will assume it is called mydir), and do
CrowdGrader will assign you submissions to review. Download each submission, and unzip it, using a Windows / Mac tool, or the command line:
unzip homework.zip -d hw_tograde_1
In the command line above, the -d hw_tograde_1 option tells unzip to create a directory hw_tograde_1 in which to expand the application; you can choose any name you fancy.
Use Android Studio to open the application in the hw_tograde_1 directory via New > Import Project. Look at the code, run the app, and follow the grading rubric.