If you come across this issue you can try the /yp reset-tools command.

If that doesn't work, then it is likely an issue with character encoding if your computer uses non-English characters. You can try the solutions listed under "Error downloading request/tools" here:
https://thunderstore.io/c/lethal-company/p/kerotein/YPlayBoombox/wiki/2732-russia-request-timed-outerror-downloading-tools/.

If you don't see ffmpeg.exe and yt-dlp.exe in your C:\SteamLibrary\steamapps\common\Lethal Company\YPlayBoombox\lib folder, you can also try downloading these manually online and place them in that location (create the folders if they don't exist).

If these solutions do not work, then you can get in touch here:
https://thunderstore.io/c/lethal-company/p/kerotein/YPlayBoombox/wiki/1909-how-to-get-in-touch/