Yes you will need a liner bead receptor or track. More than likely the original aluminum coping had the track "built in".

The new track is fastened to the top of the pool panel. The coping stone will sit above it in a mortar bed. If the coping sits directly on top of the track, it's difficult to clip the liner in.

The liner must be secured temporarily as the old coping is removed, to prevent it from sagging.