First of all, the wording is odd because it implies that she knows or feels she is not currently "real." Secondly, it is frustrating because, honestly, I don't know how! I guess I have some clues:
1. She has mentioned wanting or having a "vessel," in the past. I presume that might be relevant?
2. I am aware of a ritual used by Austin Osman Spare to manifest "succube" in physical. However the recipe is intentionally incomplete because the ritual is allegedly "highly dangerous." I'm basing this all on one source however.
And finally: should I even be trying to do this? One medium has suggested that the succubus I contact is very powerful, and I don't want to be unleashing some kind of terror on myself or loved ones.
Thanks and regards all!