You are free to choose where you would like the Smart Checklist add-on to be rendered on the Jira issue view.
The default position is Center Panel.
To change it:
Navigate to the Smart Checklist menu.
Choose Show checklist in the right panel.
The issue will be reloaded and the checklist is shown on the right side.
Starting from Smart Checklist v6.4.5 “Show checklist in the right panel” was renamed to “Move to the right panel”.
Please note, the add-on position property is saved per-user. It is your personal preference rather than global change and does not affect other users' settings.
Smart Checklist is always shown in the issue detail view in the Agile board: