This is likely due to the Member not having requested any document uploads when creating the E-sign/Document Request. 

If your patient doesn't have the Upload Documents button available for them to click through and upload their documentation, you simply need add Request Uploads via the Patient's Profile. Login to the Dashboard, click on Patients tab, find the corresponding patient that needs additional uploads and click through to their profile. 

Next you click on the Documents button, which takes you to that Patient's Document Requests page where you will see all E-sign documents and uploads that have already been requested of this patient. 

Assuming you did not select any Upload Document requests originally, hence the module not being available for them to access, click the Request More button at the bottom of the page. Here you will click on the "+Add documents" button and add whatever documents are needed from the patient from the dropdown. 

Once you have added all the necessary uploads needed to the request simply click the "Complete & notify patient" button at the bottom of the page. This will enable the Upload Documents module on the patient side and the can proceed to upload as requested.