Most acapellas from songs where computers were not controlling the drums will need warping to stay at a precise BPM over a few minutes. Depending on the genre, that’s around the early 90s and earlier but it varies and many bands still record without a click track. If you’re just playing a short sample of the acapella from a cue point juggling standpoint or something, it’s usually possible to get it in sync enough just by messing with the tempo slider.