You can export an InDesign layout that uses Ajar Productions's Universal Scrolling Frames in an EPUB from via File > Export without any additional steps.

However, if you'd like to export an InDesign layout that uses Scrolling Frames an EPUB from the Book panel, you'll need to specify that it uses the CSS for Scrolling Frames. Here's how:
  1. In the Book panel, select the the document to export.
  2. In the Book panel flyout menu, select Export Book to EPUB...
  3. In the Export dialog, give the EPUB a filename and click Save.
  4. In the EPUB - fixed Layout export Options dialog, click on the CSS section.
  5. Click the Add Style Sheet... button
  6. Navigate to the scrollingframe_epub.css file
    • On macOS:
      • MacintoshHD:Users:[username]:Library:ApplicationSupport:Ajar Productions:scrolling frames:scrollingframe_eub.css
    • On Windows:
      • C:\Users\[username]\AppData\Roaming\Ajar Productions\scrollingframe\scrollingframe_epub.css
  7. After selecting the CSS file, in the Open a file dialog, click Open.
  8. In the EPUB - fixed Layout export Options dialog, click OK.

TIP: If you have trouble locating the CSS file, simply check FXL EPUB export settings an InDesign document where you've applied Scrolling Frames (the extension automatically applies the CSS file there).

Note that Ajar Productions doesn't control the EPUB or Publish Online exports, so there can sometimes be quirks of those two formats that we cannot address. However, we do have full control of in5. For best results when using Scrolling Frames, export your documents with in5.

To create documents that use Scrolling frames and add even more interactivity, try Ajar Productions' in5 plugin for InDesign.