• Same account: Copy map
• Another account, same server: open the link, copy map
• Another server: Create map → Import → Map from another server
• File for backup or handover: export the map as JSON, import later
• Duplicate account at school: the school admin merges the accounts
• Parts only: copy an external column or box
• One copy per student: distribute the map to a group

Your content belongs to you. With these ways, you can get it anywhere you need it.