Windows server 2016 standard is supported if using version 10. If using a previous version, it is still likely to work. For a list of compatible operating systems, please see this KB article.

Just to reconfirm the below as per the customer query:

the issue is that the customer is planning to upgrade their Domain Controllers. The DC operating system will be upgraded to Windows Server 2016, our concern is the Domain Functional Level specially for the systems that are using (Single Sign On) such as Laserfiche.

We need your confirmation that raising the domain functional level to windows server 2012 R2 or even to windows server 2016 will not affect users authentication with Laserfiche system by any means.  

Note: current Domain Functional Level is windows server 2008.

Appreciate your confirmation on the above so we can give a go ahead to the customer accordingly.