Follow the below steps:
Add it as an embed HTML
Publish your document by clicking File > Publish to the web.
Copy HTML embed code. Select embed, and copy the embed code
Go to your course and choose “embed HTML” capsule
Paste the code, and your document will display
Add it as a PDF capsule:
Click File → Download as → PDF document (.pdf).
Go to your course, choose the pdf learning capsule
Attach the Google Docs, Sheets, Slides, Forms, etc.