If you want to be part of the dedicated servers Player Test Build, you will need to update the PTB to 2.7.0a. The dedicated servers will be turned on the PTB without a patch. As long as you have the 2.7.0a version of the PTB, you will be able to test dedicated servers.
Patch notes: https://forum.deadbydaylight.com/en/discussion/59071/2-7-0-mid-chapter-player-test-build