Hi Thiago,
It could be that sapjco3.dll is not recognized on Windows 8.1 (according to SAP note 1077727 it's not listed in the officially supported OS). However - as the message states: "If you don't develop a JCo scenario for HANA Cloud, you can ignore this issue." - the server should be up and running other than that.
Cheers,
--Vlado