There is no activation required, the whole SPI processing is done in the library code.
On a Colibri T20, tarting with a call…
HANDLE hSpi = Spi_Init(L"SPI4");
…is sufficient to use SPI 4 on GPIOs D0 (CLK), D4 (MOSI), D1 (MISO) and D3 (CS).
Regards, Andy