There are several ways to turn on windows update windows server, both automatically and manually. Basically Windows Update aims to update or improve your Windows server operating system, to minimize the presence of malware or viruses.
Open the Powershell Start > search > Powershell.
Then type in: sconfig
Then select number 5 and follow by typing A
References:
A means set to Automatic
M means set to Manual
D means only downloaded, but pending (not yet installed)