Whenever a document is pending a user's approval, they receive an email notification similar to the one below: 

This email contains the following details:

  1. The task name in the email title.
  2. A link to perform the task.

To take action, the user can start by clicking on the link to perform the task. They will then be directed to the page below:

At this stage, the user's can take action or consult the workflow history details directly from the page just as they would in Drive.

Note this approval method is mobile-friendly and allows users to take actions on the go, directly from their smartphones or tablets. 

The only requirement is for users to be logged in with the appropriate Google account, whichever device they are using.