CC Buchner download error

[pkoe1975]

ebookdownloader@1.0.0 start
node --no-deprecation src/EbookDownloader.js

√ Publisher / Website » C.C.BUCHNER - click & study
√ Email (Empty to read from config.json) ... my.email.at.home@gmail.com
√ Password (Empty to read from config.json) ... ********
√ Overwrite old temp files ... yes
√ Select a book » Mathe.Logo Bayern 9 I – neu
√ Selectable text ... off / on
deleted temp files
created folder: ./out/DownloadTemp/Mathe.Logo Bayern 9 I neu/
downloaded 0/310 pages
node:events:497
throw er; // Unhandled 'error' event
^

Error: spawn ffmpeg ENOENT
at ChildProcess._handle.onexit (node:internal/child_process:285:19)
at onErrorNT (node:internal/child_process:483:16)
at process.processTicksAndRejections (node:internal/process/task_queues:90:21)
Emitted 'error' event on ChildProcess instance at:
at ChildProcess._handle.onexit (node:internal/child_process:291:12)
at onErrorNT (node:internal/child_process:483:16)
at process.processTicksAndRejections (node:internal/process/task_queues:90:21) {
errno: -4058,
code: 'ENOENT',
syscall: 'spawn ffmpeg',
path: 'ffmpeg',
spawnargs: [ '-f', 'jpeg_pipe', '-i', '-', '-f', 'image2', '-' ]
}

Node.js v22.9.0

I love using this tool, and my other downloads (cornelsen, klett) work like a breeze. only cc buchner always shows this error.... Any idea appreciated.
Thanks, Pete