You can used Active directory (NTNAME) in section access instead of user name and password where you don't need password.
LOAD * INLINE [
ACCESS, NTNAME, REDUCTION
NUM AS REDUCTION;
Chr( RecNo()+ord('A')-1) AS ALPHA,
RecNo() AS NUM
REDUCTION is field from dataset on which you want to apply section access.
Dont forgot to check Data reduction and strict exclusion from Document Setting>> Opening.
Go through below link for more details,