How can I allow authors to upload final presentations?

Is it possible to allow authors of selected abstracts to upload their final presentation?

Yes, you can allow authors to upload final versions of their abstracts and presentations by creating a file upload field in the Basic Setup > Submission Questions section under Abstracts & Reviews module. 

To restrict uploads to authors with accepted abstracts, select the option "Accepted submissions" for that field. You can also set a submission deadline for these uploads, under the field editor. 

Authors will then be able to log into their dashboard and upload their final papers and presentations accordingly.