PTB stands for "Public Test Build". It is a chance for players to be able to test upcoming features. Currently, the PTB is only available to players on Steam.
- Right-click Dead by Daylight in your Steam library
- Select "Properties"
- Head into "Betas", then select Public Test Build from the list
If this option does not appear, then it is likely a PTB build is not currently live.
Note: When joining the PTB is may seem as if you've lost progress. This is intentional, and you can learn more about it here.