The Paste as New Clip button is only available on the collection toolbar when the ClipHistory tab or an AceText Collection tab is active.
Click the Paste as New Clip button or press Shift+Ctrl+V to create a new clip from the text on the Windows clipboard, regardless of which application copied the text to the clipboard. If you used Copy to Clipboard in AceText to place several clips and/or folders on the clipboard, all of them will be pasted.
Note that the keyboard shortcut Shift+Ctrl+V pastes the text as a new clip, while the regular paste shortcut Ctrl+V will paste the text into the control that has keyboard focus. E.g. if you are editing a clip's label, Ctrl+V will paste the text on the clipboard into the label.
See Capture, Enter and Store Text and Manage and Arrange Text to learn how to use AceText.