Hello,
thanks Vincent.
I fixed it too.
In a different way but the root cause is the same discovered by you.
Basically in the C:\Program Files (x86)\PDF24\gs\ folder the bin folder is missing.
I think it's due to an error during the update (and the 9.0.3 solved a problem with GS...).
If you uninstall the installed version and then install the new one, the bin folder is created correctly.
Thanks,
Andrea