After having installed the app from the Atlassian Marketplace, you can start using Version Sync right away!
Company-managed projects: Navigate to Project > Project settings > Version Sync
Team-managed projects: Navigate to Project > Project settings > Apps > Version Sync
If no versions are visible in your team-managed project, you have to activate Releases and versioning first: Project > Project settings > Features > Releases and versioning
To sync versions between projects, you can create groups, which contain (source or target) projects. There are two kinds of groups: