You can follow below instructions to setup S-Drive for Cases.
- Go to https://login.salesforce.com and login to your Salesforce account.
- Go to Setup -> Customize -> Cases -> Buttons, Links and Actions. Click Edit on the left of View label.
- Select Override With Visualforce Page and then select CaseFilePage [cg_CaseFilePage] from the dropdown. Click Save button.
- Go to Cases tab and select a case. Scroll to the bottom of the case detail page. You’ll see Case Files section.
- Now you can create folders, upload files etc. to your cases using S-Drive.