You can configure the Salesforce Mobile app to show the S-Drive tab as well as showing files on Accounts and other objects.
In order to display S-Drive Tab on Salesforce Mobile App Navigation Menu, add the S-Drive Mobile Tab to Salesforce Mobile App Navigation Menu.
Go to Setup and type "Salesforce Navigation" in the quick find box and click on it
Add S-Drive Mobile Tab from the Available section to the Selected section.
You can now see S-Drive Mobile on Salesforce Mobile App navigation menu
Tap on S-Drive Mobile to see your S-Drive Tab files.
S-Drive on Objects
To view S-Drive in the mobile app on objects such as Accounts, Cases, etc, you'll need to edit the object's Lightning page, add the S-Drive Lightning component and configure its form factor for phone. The steps are as follows and are done from within Salesforce on your desktop (not from the Mobile app.)
Edit the Lightning page for the object where you want to configure S-Drive for mobile.
Either go to the Object through Setup and go to Lightning Record pages and edit the page
Or go to a record for the object (for example, go to an Account) and click the gear wheel and Edit Page.
From the list of components on the left side, drag the S-Drive Lightning component and drop it on the page.
Configure the component as you would normally do, but check the box for "Use Compact View"
Under "Set Component Visibility" at the bottom of the configuration, choose "Add Filter."
Under Filter Type, choose Device.
Configure it for Form Factor Equals Phone
You probably already have an S-Drive component on your page. Set the form factor for that one to Form Factor Equals Desktop.
If you'd like S-Drive to show in Compact View on your Desktop, you can configure just one S-Drive component. The component will show in both Desktop and Phone by default.