Couldn't find a download link

[Dst901]

Hello,
I have this error
Is it because the book is not downloadable?

[2025-01-16 10:16:06,891] INFO: Extracted the table of contents to toc.json
[2025-01-16 10:16:06,892] INFO: Wrote human-readable table of contents to toc.txt
[2025-01-16 10:16:06,892] ERROR: Error! Couldn't find a download link for 93 pages (100.00% missing, total: 93 pages).
[2025-01-16 10:16:06,892] INFO: Starting to download 93 pages…
[2025-01-16 10:16:06,892] ERROR: [1/93] Skipped: download link for PP1 is missing…
[2025-01-16 10:16:06,892] ERROR: [2/93] Skipped: download link for PP2 is missing…
[2025-01-16 10:16:06,893] ERROR: [3/93] Skipped: download link for PA1 is missing…
[2025-01-16 10:16:06,893] ERROR: [4/93] Skipped: download link for PA2 is missing…