A slightly misleading typo, you require knowledge of 6561 to allow this quest, not 'don't have knowledge' on it. 6561 incidentally is Shaking: Skilled, and requires Artisan 1 in processing to unlock (via the rewards tab).

TOHAVE:

Processing: Professional 5
Gathering: Skilled 10
Have knowledge on Shaking: Beginner
Have knowledge on Drying: Beginner
Have knowledge on Filtering: Beginner
Have knowledge on Grinding: Beginner
Have knowledge on Heating: Beginner
Have knowledge on Chopping: Beginner



In ordert to unlock this quest from the NPC, is necessary to complete the next quest chain:

1- https://bdocodex.com/th/quest/3208/1/
2- https://bdocodex.com/th/quest/3208/2/
3- https://bdocodex.com/th/quest/3208/3/
4- https://bdocodex.com/th/quest/3208/4/
5- https://bdocodex.com/th/quest/3208/5/
6- https://bdocodex.com/th/quest/3530/223/
7- https://bdocodex.com/th/quest/3530/224/

After completion, speak again with NPC Murghed and takes you on autopath to Behr, once there complete the next quests:

8- https://bdocodex.com/th/quest/3530/225/
9- https://bdocodex.com/th/quest/3530/226/

Once you complete all this quests you are availble to take the quest:

10- https://bdocodex.com/th/quest/3510/80/

Hope it helps!