Make sure you have sufficient permissions to call the cmdlet, you will need the RoleManagement.Read.Directory scope consented to. Here's a working example:
Connect-MgGraph -Scopes RoleManagement.Read.Directory
Get-MgRoleManagementDirectoryRoleEligibilitySchedule -Filter "principalId eq '00f475c3-ef4d-41d3-afb1-73d76ab8a9fa'"