Internal Server Error at the "Module: Digital Rights Management (DRM) and Encryption"

I finished the `INSTALL.md`, so I step up with the `workflow/drm-vod.md`, After I did the "Test link", The API returns this:
```
{
"message": "Internal server error"
}
```
Did I do something wrong or I have another step to take before `INSTALL.md`?

Start with INSTALL.md and workflow/drm-vod.md, then reproduce the documented "Test link" request and capture the API response. Trace the request using the repository's available entry points to identify why it returns "Internal server error"; done means the documented workflow succeeds or the missing setup step is clearly identified.

Written by the indexing model from the issue text.