With Cascade, you'll need to select it each time as opposed to the documents opening in separate windows as before? Thanks.
Hi all,
This is to update you that the feature is available in Acrobat now. If it is disabled, please check this preference.
The preferences settings control how the application behaves whenever you use it; they are not associated with any particular PDF document.
1. To access the Preferences dialog, choose the hamburger menu(Windows) > Preferences or Acrobat / Adobe Acrobat > Preferences (macOS).
2. In the Preference's dialog box's left pane, select General, then uncheck the "Open documents as new tabs in the same window(requires relaunch)"
3. Click Ok
4. Relaunch Acrobat

To know more about opening documents: https://helpx.adobe.com/acrobat/using/opening-pdfs.html
Let us know if that helps.
~Tariq