Unless the script did something custom the reference level (so the denominator) is always the condition that alphabetically comes first. That is because these conditions are converted to factors and the factor levels are sorted alphabetically. So here it is probably conditionB/conditionA so a positive logFC means higher in B.
Seems it is just standard settings, so A should be the reference (=denominator), I think. If that tool returns the normalized counts you can simply check for some genes whether a positive logFC means higher counts in samples of B rather than A.