Auto-Mapper in asp.net core for complex relationship

Requirement: ------------ I need to map the main DTO 'Definition' class with the View Model 'MembershipTypeDefinitionVM' using Auto-Mapper in Asp.net core 3.1. I was able to map all the fields except 'Level0FeeStructure' and 'Level1FeeStructure' to the 'FeeStructure' DTO. Please Note the 'Definition' entity has many-2-many relationship with the 'FeeStructure' entity, that's the reason we had to create a joining entity called 'DefinitionFeeStructure' which has one-2-one relationship with 'FeeStructure' entity. Where as in my view model i do not need the joining entity instead we want to directly map the 'FeeStructure' entity to the main view i.e. 'MembershipTypeDefinitionVM' as 'Level0FeeStructure' or 'Level1FeeStructure'.

Question:
---------
1. How do i map complex related fields like the one mention above?
2. Do i need to separately map the fields? if yes then how?

When i run the application it throws me the below exception:
------------------------------------------------------------
AutoMapper.AutoMapperMappingException
  HResult=0x80131500
  Message=Error mapping types.
  Source=AMS.Web
  StackTrace:
<Cannot evaluate the exception stack trace>

Inner Exception 1:
AutoMapperMappingException: Error mapping types.

Inner Exception 2:
AutoMapperMappingException: Missing type map configuration or unsupported mapping.

Below are the entity classes and the Mapping profile.

DTO:

Main DTO Class:

public partial class Definition
{
    public Definition()
    {
        DefinitionFeeStructure = new HashSet<DefinitionFeeStructure>();
        MembershipDocumentRequirement = new HashSet<MembershipDocumentRequirement>();
    }

    public int Id { get; set; }
    public string Name { get; set; }
    public int CategoryId { get; set; }
    public int TypeId { get; set; }
    public bool IsMembershipExpire { get; set; }
    public int Tenure { get; set; }
    public bool IsReferenceRequired { get; set; }
    public bool IsByInvitation { get; set; }
    public OrganizationLevelEnum OrgLevelId { get; set; }
    public bool IsPersonalInfoRequired { get; set; }
    public bool IsProfessionalInfoRequired { get; set; }
    public bool IsEducationalInfoRequired { get; set; }
    public DateTime CreatedDate { get; set; }
    public string Abbreviation { get; set; }

    public virtual ICollection<DefinitionFeeStructure> DefinitionFeeStructure { get; set; }
    public virtual ICollection<MembershipDocumentRequirement> MembershipDocumentRequirement { get; set; }
}

Related DTO Class:

public partial class DefinitionFeeStructure
{
    public int Id { get; set; }
    public int DefinitionId { get; set; }
    public int FeeStructureId { get; set; }

    public virtual Definition Definition { get; set; }
    public virtual FeeStructure FeeStructure { get; set; }
}

Related DTO Class:

public partial class FeeStructure
{
    public FeeStructure()
    {
        DefinitionFeeStructure = new HashSet<DefinitionFeeStructure>();
        FeeLineItems = new HashSet<FeeLineItem>();
    }

    public int Id { get; set; }
    public int OrganizationLevel { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public int DisplayOrder { get; set; }
    public int IsPayNow { get; set; }

    public virtual ICollection<DefinitionFeeStructure> DefinitionFeeStructure { get; set; }
    public virtual ICollection<FeeLineItem> FeeLineItems { get; set; }
}

View Model:

public class MembershipTypeDefinitionVM
{
    public int Id { get; set; }

    [Required(ErrorMessage = "Please enter name")]
    public string Name { get; set; }
    public int CategoryId { get; set; }
    
    [Display(Name = "Membership Category")]
    public string CategoryName { get; set; }
    public int TypeId { get; set; }
    public string TypeName { get; set; }
    public OrganizationLevelEnum OrganizationLevel { get; set; }
    public FeeStructureDefinitionVM Level0FeeStructure { get; set; }
    public FeeStructureDefinitionVM Level1FeeStructure { get; set; }
}

Mapping Class:

public class MembershipTypeProfile: Profile
{
    public MembershipTypeProfile()
    {
        CreateMap<Definition, MembershipTypeDefinitionVM>()
        .ForMember(a => a.Level0FeeStructure, b => b.MapFrom(c => c.DefinitionFeeStructure.Select(d => d.FeeStructure)));
    }
}