I just bought the holder 2-3 weeks ago to retry it. I keep it in the bathroom for easy clean up & I'm glad I did, as she peed
beside almost every time. So I started keeping a pad next to the one on the holder. She used it right away.

I've been slowly layering the pad over the one on the holder little by little and she's been going "on target" most of the time. 9/10 times she tells me when she's gone so I go in there, point, say potty, good girl, treat, etc. If she shows me she's done it on the floor I clean it up with the pad & show her, praise, etc. once she sees it on there.
Today just the holder was out & she used it when we were home. But poop is a different story, she still insists on doing this right in front of the toilet.
It might take some time but I'm sure they'll catch on soon. Good luck.