I use Dreamwer CS6 on Windows 11 for years. Today, the Dreamweaver program will not open.

This should work ONLY IF you bought the program and registered it in the past - not a trial, but the full version ONLY - and it stops opening because it needs to re-register: So, if you try to open DW and get the pop-up that says it needs to connect to the internet because it needs to verify, there should be highlighted / linked text that says to ativate offline. Click on that, generate a code, and then go to https://exception.licenses.adobe.com/aoes/aoes/v1/IMSLogin (if you’re not automatically logined in, login). There’s another link on that page to Gnerate Response Code  Then enter the code you copied and your serial number and you should be good to go.

Please read this help article about Activating the License for Legacy Apps

https://helpx.adobe.com/download-install/apps/troubleshoot/licensing-activation-issues/cant-activate-reinstall-legacy-apps.html

Registration is not the same as License Activation. Two separate things.

1. Every new installation requires License Activation.

2. Individual users get 2 Activations per product license.

3. After 2 Activations are used up, you must deactivate CS6 from a previously installed device, or find new software.

You must license your software to escape from Trial mode.

Find your serial number for Dreamweaver CS6 by logging in to your online account.

https://account.adobe.com/products

Windows users may be able to recover lost serial numbers with this free tool from Belarc.

http://www.belarc.com/free_download.html

Failing that, Visual Studio Code with integrated browser is the closest thing to WYSIWYG. 

https://code.visualstudio.com/docs/debugtest/integrated-browser

What error are you receiving? If it is about exceeding your activation limit, then you need to open up your old computers and deactivate the licenses on those before you will be able to install. If you don’t have access to those unfortunately Adobe no longer resets activation counts and you may need to consider alternative solutions. If it is another error please post what you are seeing and we can try to guide you if this is an installation error that can be overcome or a licensing error that may not.