Thank you very much. It works well.
How to do it ?
First step :
Download Fiddler.
Step 2 :
USE THIS METHOD to setup Fiddler, don't downgrade to 3.0.0, skip to Part 2 and setup your fiddler settings.
Step 3 : Download
SSL Pinning Bypass (youtube tutorial is outdated on this post).
Step 4 : Start Fiddler.
Step 5 : Start DbD. When the EasyAntiCheat blue loading bar is 1/3 loaded, start SSL Pinning Bypass.
Step 6 : When the game loads your profile, you should see "steam.live.bhvrdbd" lines appear on Fiddler, double click on one of them, switch to "Cookies" tab, then you get your Cookie after "BhvrSession=". Copy it.
Step 7 : You can close the game, close Fiddler & type enter to restore the bypassed file on SSL Pinning Bypass, enter again to close it.
Step 8 : Start Save Injector, and paste your Cookie.
Step 9 : Dump your savefile.
Step 10 : Use
Save Editor to add what you want.
Step 11 : Inject your edited savefile.
Here you go.
PS : You can also change your level and rank with this Cookie, just download
this post attached folder "Sender_mpgh", rename sender.exe, start this renamed sender and paste your cookie. Change level/rank.