potty training

Hello, This is Ginny. My 5 month old basset. I have had her for about two months and we are not making much progress potty training. Situation kind of sucks. I live in an upstairs apartment – it goes directly out into a court yard where she goes – no walk necessary for a quick potty. However I need to carry her down the stairs. They are way too steep for a basset to safely go down. Hopefully moving to a downstairs apartment before she’s full grown. However, I will likely live an apartment for most, if not all her life where she won’t have quick access to a back yard. I bring her to my parent’s house often, and she doesn’t go inside nearly as much because she has easy access to the back yard. I take her out as freaquently as I can. She often goes pee as I am putting my shoes on. Bottom line is, she must learn to hold it until I bring her out, or scratch at the door. Im pretty good at predicting when she might need to go, but Im not perfect. I bought a button for the door that rings, but I can’t train her to push it with treats, let alone push it when she needs to go potty. I think going to the door will come naturally with learning she can’t go inside. She never goes in her crate, which she sleeps in for 8 hours. occasionally she is in her crate for up to 4 hours during the day. So I know that she knows how to “hold it”. Getting her to hold it outside the crate however, I’m lost.