ShortDynamicLink is not generating short link for dynamic links
What is the long link you are getting? I suggest trying long link and ensure the link works correctly.
Also, append &d=1
to long link. Such link will navigate to debug page with possible errors/warnings displayed.
Looking at your code, one possible reason for failure is format of the domain. See example https://firebase.google.com/docs/dynamic-links/android/create . Domain expected to be string containing only domain, without https scheme:
.setDynamicLinkDomain("abc123.app.goo.gl")