Dreamweaver CC2015 was the last version where the panels worked. You can install previous versions of Dreamweaver along with the latest.
How to join two versions?
The two versions cannot be joined, you can install both, they will live alongside each other, but cannot run at the same time.
So I only use a 2015 version? And how can I download this version?
In my Adobe Creative Cloud you do not have an option: "Other Versions"
Update the CC app
Other Versions are not available to Trial members. You must have a paid subscription.
Can not really put these panels on?
I have the deprecated DB panels because one of my extensions from WebAssit piggy backs on top of it. However, I do not use the old panels to generate code as it is sorely out of date.
I kept DW CC 2017.0 so I could continue using the panels extension.
I obtained the extension from DMX Zone.
And I used the Extension Manager from DMX Zone to install it.
I installed Dreamweaver 2015 and do not have these panels yet.
The panels were removed from DW CC. You must download the extension & extension manager from DMX Zone (see correct answer above for the links).