C:\temp>dir /b \wkhtmltopdf.exe /s

C:\Program Files\wkhtmltopdf\bin\wkhtmltopdf.exe

C:\Strawberry\wkhtmltopdf\bin\wkhtmltopdf.exe

Just an FYI. I tried the source code on a Ubuntu box with no bin lines at all and it comes back with the same error.

Couldn't find command '/usr/bin/wkhtmltopdf' at /usr/local/share/perl/
+5.30.0/MooseX/Role/Cmd.pm line 117
[download]

I think the bug is in the MooseX::Role module.