I can't get any answers on this product, and my project is paralyzed.

All I want to do is glue a vinyl sheet to a concrete shower pad, to make a waterproof lining and better looking floor in the shower.

Its basically a pressure sensitive adhesive, and I've got many confirmations that it can be used to glue vinyl to concrete.
This product also says it can work in high moisture conditions, etc etc.
Even though I don't see how the water would get through the vinyl sheet to where the glue on the other side is, so that seems to be not so much of an issue.

But what I'm trying to determine is, do you need to use a concrete sealer first?
Or will that make it not stick.
I'd love to do this correctly, but I can't get anyone to tell me the correct procedure. I obviously don't want to do it incorrectly and have it come up later.

Can anyone help, without being negative or telling me to rebuild from scratch?

If I could afford to do that, I wouldn't need to be in this forum right.

Thanks