[Table("users")]
public class User
{
    [Key]
    [Column("id")]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [Column("name")]
    [StringLength(15, MinimumLength =2)]
    [Required]
    public string Name { get; set; }

    [Column("password")]
    [StringLength(100)]
    [Required]
    public string Password { get; set; }

    [Column("email")]
    [StringLength(30, MinimumLength =6)]
    [Required]
    public string Email { get; set; }

    public List<UserActivityPoints> Activitypoints { get; set; }
}

[Table("activitypoints")]
public class UserActivityPoints
{
    [Key]
    [Column("type")]
    public int Type { get; set; }

    [Column("amount")]
    public int Amount { get; set; }

    [Key]
    [Column("user_id")]
    public User User { get; set; }
}

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<User>().ToTable("User");
    modelBuilder.Entity<UserActivityPoints>().ToTable("activitypoints");
}

var i = ProductionDbContext.GetInstance().Users.Find(1).Activitypoints;