A big button to log in will appear in the middle of screen. Use it.
Log in to your account.
You should be able to use Shared drive now!
To add a new file use the "+" button.
You should see your uploaded file.
You can edit your file by clicking on the three dots icon.
Using the button next to the three dots will enable sharing menu. You can create a share link for your file using the "+" icon and copy it to clipboard.
You can create a share link for your file using the "+" icon and copy it to clipboard.
With the link, you can share your file win anyone.
You can see note next to your file that it has been shared.