Download the "out-of-the-box" version from the path /etc/fmdita/dita_resources/DITA-OT.zip in your AEM instance.
The file (DITA Open Toolkit) is used by Adobe Experience Manager (AEM) Guides and Adobe FrameMaker to generate output formats like PDF and HTML from DITA content. Guide: Creating a Custom DITA-OT.zip ot.zip
It is highly recommended to run the integrator tool on a Mac or Linux system to ensure file path compatibility across platforms. Re-package the ZIP ot.zip