If you have admin access you can set up a delegation on behalf of a user who is out on vacation or not available to approve documents for a while. Please follow the steps below:
Go to Admin.
Click on Manage Users > Users on the left Menu.
Click on the Delegation tab.
Click on the New Delegation button.
Add the details in the delegation form.
If you'd like to also assign Pending Approval requests to the delegated user, please mark the "Assign Pending Approval requests" checkbox.
Click on Save.