Can I attach pvc conduit to an existing chain link I am installing a storage shed and I don’t want to dig a ditch
Whether the fence is deemed a permanent structure suitable for support of electrical conduits is likely in a gray area and subject to the determination your local inspector makes. You could call in advance and ask.
PVC conduit has to be supported with a maximum distance between supports determined by the size and type of conduit. For example, 2" schedule 80 PVC supports can be no more than 7 feet apart. Schedule 40 has to be closer, and smaller conduits have to be closer. PVC tends to sag and look like hell if you don't support it at the code maximum between supports.
So unless your posts are very close or your conduit is very big, you'd have to fasten to the chain link part of the fence, which may or may not be deemed sufficiently rigid for conduit supports, or run something like unistrut from post to post, and attach to that.
But that would be a big pain and at that point, you might be better off with EMT, which can span 10', or RMC, which with threaded couplings can span 12' between supports. You might still need to put some strut between some of the posts if there are boxes or etc. that need closer support.