As swiv3d said, you should download the driver from Oppo. Prior to Windows 10 you would need that driver to do sample rates over 96 Khz, although current Windows 10 now supports higher sample rates natively.
In general, the recommendation is to use ASIO over WASAPI, since the ASIO driver is customized by the manufacturer, whereas WASAPI is a generic system. However, the manufacturer may or may not do much relevant customization to the generic ASIO driver that is available from Steinberg, the originator of ASIO. That said, there should be little to no difference in sound between ASIO and WASAPI.
ASIO is required for native DSD, which the HA2E requires for DSD256. For DSD64 and DSD128, the device may support DoP, which can be used with WASAPI.
Bottom line - ASIO is the preferred choice, although WASAPI should be fine except for DSD.