Continuous ATP is similar to Peak phase during a progression but that normally entails reaching 3 stars or higher TL. Library choices expand as you reach 2 stars and higher.
You can continue to do what you’ve been doing in the past by manually selecting workouts.
If you want to see all the 30-minute options, go to the Workout Library and set Max minutes to 40 under Filter. That will list some just over 30 minutes, but you can always shorten the cooldown or skip ahead if 30 is all you have time for.
Also search the Sessions Library for up to 40 minutes. There are some high intensity options I think you’ll enjoy.
As @wescaine mentions you can locate other workouts of interest and shorten them. To do that view the workout, determine if easily shortened, select Open in Designer, then Copy button in lower right, make your modifications, and Save. The workout is added to your Personal folder with “- Copy” appended to title.
Lots of newbie tips posted here – Beginner questions