How do I add custom maps to the mapcycle in Killing Floor 2

First, please stop your server.
Once it’s stopped, switch the server to Advanced mode.
This is necessary because we need to edit the PCServer-KFGame.ini file.
Click on PCServer-KFGame.ini in the white column on the left.
First, find the line:
GameMapCycles=

This line determines the maps that are in the cycle.
For example, if the map was KF-Testmap1, the complete line would look like this:
GameMapCycles=(Maps=( "KF-Testmap1" ))

With more than one map, the line would look like this:
GameMapCycles=(Maps=( "KF-Testmap1" , "KF-Testmap2" , "KF-Testmap3" ))

Next, a new section needs to be created.
It looks like this:

    [KF-Testmap1 KFMapSummary]
    Mapname=KF-Testmap1

Create this section for each custom map and adjust the map names accordingly.
Once you’re done with your changes, click Save.