Each version of Lightroom only supports RAW files from certain cameras. When a new camera model is available, Lightroom has to be updated to support RAW files from the new camera. You need to update to a newer version of Lightroom to support your camera.
Camera RAW is a plugin for Photoshop, not Lightroom. You can't install Camera RAW in Lightroom.
The 7D from 5 years ago has been supported since LR 2.6.
If this is a 70D rather than a 7D, then you’ll need LR 5.2 and if this is a 7D Mark II then you’ll need LR 5.7 which isn’t out yet.
If you are getting a message that the “files cannot be read” this means the destination folder specified in your LR import panel is either incorrect or the permissions for it don’t allow LR to write files, there.
You are right - I was mistaking on the camera I had bought (!?) It was the 70D.
I will try upgrading to 5.2
Thank you for your help - it seems like this will work