If your DW encoding file is correct, yes. There’s just no meaningful diffusion analysis you can do with just 3 volumes… And judging by the fact that you’re trying to provide a 65 DW direction encoding, I’m guessing you’re expecting your data to match that - they don’t.
More or less what you had, but just provide the enclosing DICOM folder for the input data. And if your DICOM data are half-decent, you shouldn’t need to provide the DW encoding separately, it should already be in the DICOM headers. So this might look something like (depending on where your DICOM data reside):
dwipreproc -rpe_none 2 ./Downloads/anger/DICOM ./Downloads/anger/anger_out.mif
If you still get an error about the DW encoding not matching, then my guess is either the data you’re trying to process are not the raw diffusion data, or they were produced by some non-standard implementation (data from the 3 major MRI manufacturers should be fine). Bear in mind that the data may look like a diffusion sequence, but might correspond to a derived metric; for instance, on Siemens scanners, you’ll often find the raw DW series, followed by other similarly named series that correspond to the FA, MD, DEC, etc. (my guess is you have the DEC, given that it comes out as 3 volumes). You need to pick out the raw DW series.