in spanish they use a softer "d" than in english, the tongue is a little further forward, almost making a "th" sound as in the word "the".
Compared to English /d/, the tip of the tongue is always further forward for Spanish /d/, contacting the upper front teeth. It is pronounced as a voiced dental stop [d̪] after a pause, /n/, or /l/, and as a voiced dental approximant [ð̞] everywhere else.
I am having a hard time with the mic lessons. The app doesn't understand me ever. I don't speak Spanish the way it does, I'm so used to hearing 'broken' Spanish.