Before going ahead with the below, ensure that you are logged into LEX with your Service Account email. This email could be something like firstname.lastname@example.org or something similar.
To regrant access to NetDocuments, please follow the instructions below.
First, go to Control Panel, then under General, click on Manage Integrations.
Then click on Configure under NetDocuments.
Then click on Give Consent.
Then you are done!
1. After granting consent, it would be beneficial that you send email@example.com an email saying you have done this.