Quarantine Administrator - more rights needed?

Anonymous2115 

If you have the newer Defender Unified RBAC/"Microsoft 365 Defender" roles (which I believe requires certain levels of Defender licensing, possibly Defender for Office 365 P2, but I am not certain) - you should probably use this https://security.microsoft.com/mtp_roles (you may have to migrate/import existing permissions from Endpoint/Email and Collaboration permissions, such as Security Administrator or Security Operator, or Quarantine Administrator)

If not, you may still be using Email and Collaboration Roles - which you should be able to check and access here to set Quarantine Administrator https://security.microsoft.com/emailandcollabpermissions

Not directly related to your issue, but may be related to IMPORTING any permissions to Defender Unified RBAC are:
Defender Endpoint Permissions: https://security.microsoft.com/preferences2/user_roles
Azure AD Roles: https://security.microsoft.com/aadpermissions
Cloud App Security Roles: https://security.microsoft.com/cloudapps/permissions/roles
Email and Collaboration Roles: https://security.microsoft.com/emailandcollabpermissions

But, again, I would highly encourage you to move to Defender Unified RBAC if it is available to you to simplify things. This article should walk through enabling RBAC if you can: https://learn.microsoft.com/en-us/microsoft-365/security/defender/activate-defender-rbac?view=o365-worldwide

And then you should be able to access/migrate to the RBAC Roles here: https://security.microsoft.com/mtp_roles 

You may have all of these, you may have two of these, you may just have one of them. I have tenants that have been around for various points as they created the Defender Endpoint roles and started centralizing/combining role permissions to all the Defender products, so I think I have all of them, or nearly all. Best advice is just try each one of the portal links mentioned above and you may be able to see them in your own environment here https://security.microsoft.com/securitypermissions 

Where possible, use the newer style of permissions to avoid having to migrate later.