A zaouiat is a sanctuary where a very religious man is buried. They are recognisable by their roofs, decorated in green ceramic. At Ahansal, the town of Sidi Saïd has been preserved in this way: he was a holy man from the 17th Century.
Be aware that there are actually two villages at Zaouiat Ahansal. There is the modern village, over from the old village, where the zaouiat of Sidi Saïd can be found. I'd advise visiting the old village of Zaouiat Ahansal: the fortified buildings (tighermt) there are definitely worth a look, with their splendid, if slightly dilapidated, towers.
If you have time to spare, take the path from the exit of Zaouiat Ahansal and head to the village of Tarhia, a two-hour walk. There, I saw a spectacular mountain amphitheatre at the entrance to the Tarhia gorge, with cliffs which reach several hundred metres in height. It's ideal for mountain climbers!