Issue loading Dreamweaver

1.  Is Apple's newest OS in public release or is this still a beta (testing) version?

Adobe products are not certified to run on betas.

2. Is your local site folder defined? 

Does your site folder reside on your computer's primary hard drive? 

Did you try restoring preferences? https://helpx.adobe.com/dreamweaver/kb/restore-preferences-dreamweaver.html#:~:text=Reset%20preferences%20for%20Windows&text=Hold%20down%20the%20Windows%20key,Preferences%20dialog%20box%2C%20click%20Yes.