You must have the Global Administrator or Exchange Administrator role assigned to your account.
Microsoft transitioned to a "Modern" interface to improve speed and security. Modern EAC Classic EAC (Legacy) Clean, fast, mobile-friendly Tab-heavy, slower Search Global search across all objects Limited to specific views Security Supports Modern Auth (MFA) natively Often requires extra config Availability Primary for M365 Being deprecated exchange admin center download
If you're trying to set this up for the first time, let me know: Are you using or an On-Premises server? Do you need help with PowerShell commands or the Web UI ? Are you trying to fix a specific error message ? You must have the Global Administrator or Exchange
If you are looking to install the entire Exchange infrastructure on your own hardware: exchange admin center download