Transmission cooler lines leak?

It’s me again. So, finally I was able to get my transmission cooler line to click into place but no matter what I do there’s still a leak. It has new O-Rings, so that’s not the issue. My question is regarding the transmission cooler line seal, it’s a round larger piece of rubber(?) That everyone keeps saying goes on the line. In the diagrams it appears to be at the end of the line possibly under the plastic cap that’s held in place by the clip, but for the life of me I cannot get bin on or figure it out, can’t find an actual image to guide me in the right direction, honestly it’s been driving me crazy as it’s gone through so much ATF fluid. Please help me so I can get my car back on the road!