The values for dRPA75-D3BJ are the following:
s6 = 0.3754_wp
s8 = 0.0_wp
a1 = 0.0_wp
a2 = 4.5048_wp
The same values are used in MRCC for SCS-dRPA75-D3BJ, but I did not find any mention of such functional with D3BJ
The values are taken from https://doi.org/10.1039/C6CP00688D