I can't run my app at my mobile

Hi all,
I have downloaded my app directly to my computer then to my Samsung mobile (Android system). Although I have 2.5 GB free in storage and 221 MB free in the ram, my mobile gives me a message of (out of space. Free up some space and try again). The size of the app is 29 MB. My Android version is 6.0.1. Can any body help me what is the problem here?