Is CoffeeCup Software still an active business? I'm noticing there hasn't been any updates to the applications and tutorials in over 5 years.

Really????, site designer has been updated not so long ago, webform builder also, updated to php8
And you are on the website.
The site designer tutorials info, videos etc are up to date, and seeing as this is your first post as a registered user, makes me wonder where you have been these last few years.