I just received my yoke yesterday, and likewise there were no clamps in my package. It was one of my first remarks made on my unboxing video after I removed everything from the box. However the quickstart guide has a picture of some clamps. Yet if you read more deeply, it states what’s included in the box, and there’s no mention of clamps on the bill of materials.
So I think you have to go out and select appropriate clamps to do this job. That’s not easy. Enter the word “clamps” into google and more likely than not you’ll get clamps that don’t have the right form for inserting into the metal slots provided. You need the right type of clamp, and the specific vocabulary to search on is not in my field of knowledge.