After effects reads it as data. Following Adobe's official help I am creating a new solid and then trying to connect the opacity expression of the solid to the data in Json. Nothing Happens. Just an error. I am not into scripting so this is new territory for me. Can anyone tell me how to do this?
As far as I know, you can't do want you want to do.
Lottiefiles and bodymovin is about exporting animation from AE to web (by means of json files, for instance). Those JSONs you download from lottiefiles.com are not meant to be imported back to AE, and there's no way to make AE projects from them [known to me at this moment].