BCKSTG offers two methods for connecting to SoundCloud:
Autofill
"During onboarding, search your SoundCloud name to pull in your profile and latest track."
Listen & Repost
Add your SoundCloud track link to the release in Releases & Pre-Saves, on the Links tab. Your page then shows a SoundCloud button on that release. When a fan taps it and signs in to SoundCloud, the track gets a like and a repost on their profile.