asp.net core mvc custom registration page

I have a very basic task in my ASP.NET CORE MVC application. so the thing is I have 2 models Subscriptions and Coupons and they have one to many relations and by using following model classes and scaffolding I was able to generate a dropDownList on coupons create page to select anyone of the subscriptions currently in the database. I am using Entity Framework for my db and scaffolding as well.

Model classes

public class Subscription
{
    public string FirstName { get; set; }

    [Key]
    public int ID { get; set; }
    [Required]
    public string Identifier { get; set; }
    public bool State { get; set; }
    [Required]
    public string Description { get; set; }
    [Required]
    public int MonthlyPrice { get; set; }
    [Required]
    public int MinMonthlyPrice { get; set; }
    [Required]
    public int MonthlyDiscount { get; set; }
    public virtual ICollection<Coupon> Coupons { get; set; }
    public virtual ICollection<RegisterViewModel> Registrations { get; set; }
}

public class Coupon
{
    [Required]
    public string CouponCode { get; set; }
    [Required]
    public DateTime StartTime { get; set; }
    [Required]
    public DateTime EndTime { get; set; }
    [Key]
    public int ID { get; set; }
    public int Discount { get; set; }
    public bool IsPercentage { get; set; }
    [ForeignKey("Identifier")]
    public int SubscriptionId { get; set; }
    public virtual Subscription Identifier { get; set; }
    [Required]
    public int ValidMonths { get; set; }
    public bool IsSponsored { get; set; }
    [Required]
    public int Length { get; set; }
    [Required]
    public int Quantity { get; set; }       

}

now I want the same drop down on my Registration page, I am using the built in registration system of Individual User accounts and I just want to include the same drop down I have on coupon page to select "subscription" I want the same one on registration page. how can I do that? AccountsController is not getting any ApplicationDbContext in its constructor parameter unlike other controllers like "couponsController" so that is why I am having trouble figuring out how to get data from database on registration page.

I know that following code helps to get me the subscription list and get only a specific property from it.

 // GET: Coupons/Create
    public IActionResult Create()
    {
        ViewData["SubscriptionId"] = new SelectList(_context.Subscription, "ID", "Identifier");
        return View();
    }

I want same sort of stuff on my registration page but dbcontext doesn't exist on AccountsController and I cannot new it up bcz I don't know what options to provide in the constructor.