1. Please read.
Disclaimer
In order to incorporate a content from Google Docs  in Quizizz, you need to have the Chrome extension installed.
You can find the Chrome extension here: 
https://chrome.google.com/webstore/detail/quizizz-ai-turn-any-websi/jnegnfbcjklhkmoihoakeijbealomipg
2. The first step is to open a Google Doc... and click on the Quizizz extension. 

3. Now click  Create a quiz

4. You are now redirected to the Quizizz website.
You are now asked the topic of the document...

5. Type your desired content.

6. Like so.

7. Now select the grade of the students you wish to create the quiz for...

8. I chose grade 11...

9. I the selected the subject...

10. Like so...

11. ...And the number of questions, from automatic...

12. To number 10...

13. Then click on generate questions...

14. Now you can chose how many topics you wish to include in your quiz. Select the ones you believe are most suitable for your purpose.

15. As you can see, I chose all of the suggested ones, taken from the document source.

16. You can also add extra topics by typing in the box and clik "add".

17. When you are ready, click on Generate questions.

18. And now you have a quiz ready to use.
That's it. You're done.

Interactive tutorial