Since you are using Google Classroom classes in EDpuzzle, you don't need the class code because your students are automatically enrolled in your class. We do this by asking Google Classroom which students are in your class and then adding them to EDpuzzle automatically. To see that you can check your "Members" section inside "My Classes".
Knowing that your students are enrolled automatically now, you can now share an assignment. You have two options to share your assignment:
Tell students to log into EDpuzzle using their Google account (press the big red Google button). They will already see your class and all the videos you assign to it now and in the future without needing to do any extra step.
When you assign a video to a class in EDpuzzle, post the link to the assignment to your Google Classroom feed. To do this, you need to click the "Post" button next to the assignment in "My Classes". Please note that you will need to do this for every assignment of each class as the assignment links are unique for each classroom. Your students can then click it in Google Classroom to access your assignment directly but they will be prompted to log in with their Google account.
In both cases, they have to log in so we can track each of your students' progress for you to see. The second option has the advantage that if you post the link to your Google Classroom feed, your students will be notified the same way as when you post any other thing on the feed. The first option requires you to remind your students to check their EDpuzzle assignments.
"BUT I HAVE A STUDENT IN MY GOOGLE CLASSROOM GROUP THAT IT'S NOT IN EDPUZZLE"
If that is the case, it's probably because the student enrolled the class after you started using edpuzzle. There is an easy solution.
To sync both platforms once a student has joined your Google Classroom group, you just need to follow these steps:
1. Go to edpuzzle.com and log into your account.
2. Go to My Classes and select the class where your student should be registered.
3. Click the "Import students" button in the top-right corner
I hope this clarifies all your doubts, otherwise, let me know, I am happy to help you further :)