Hi NiSTha-5686!
Are there any error messages when you upload your documents?
To narrow down this issue, we recommend you check your settings in the MS Forms:
*Document size: Check your document size limit when you create a new quiz
*Document type: Check if it has requirements about your upload document type.
Besides, you can also see if this Youtube video solution is worked for you. Although it is in Portuguese, you can add the subtitles to see it.