How can i make ManyToMany admin pannel on django?

I made a ManyToManyField in Django, but it dosen't seem like i can edit it in django admin.

After reading some documents, I found out that I needed to add some kind of widget, so I added filter_horizontal=('collections',) (which was shown in Django Admin ManyToManyField) but this seems to cause an error.

Here are some codes I used.

# models.py
class Product(models.Model):
    date_added = models.DateTimeField(auto_now_add=True)
    name = models.CharField(max_length=200)
    price = models.DecimalField(max_digits=7, decimal_places=2)
    digital = models.BooleanField(default=False,null=True, blank=True)
    image = models.ImageField(null=True, blank=True)
    description = models.CharField(max_length=1000, null=True, blank=True)
    description_image = models.ImageField(null=True, blank=True)

    def __str__(self):
        return self.name

    @property
    def imageURL(self):
        try:
            url = self.image.url
        except:
            url = ''
        return url

    @property
    def descriptionImageURL(self):
        try:
            url = self.description_image.url
        except:
            url = ''
        return url

...

class Collection(models.Model):
    title = models.CharField(max_length=200, null=False)
    product = models.ManyToManyField(Product, related_name='collections', blank=True)
    date_added = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.title

# admin.py
from django.contrib import admin

from .models import *

admin.site.register(Customer)
admin.site.register(Product)
admin.site.register(Order)
admin.site.register(OrderItem)
admin.site.register(ShippingAddress)
admin.site.register(TextBanner)
admin.site.register(FocusSection)

class CollectionAdmin(admin.ModelAdmin):
    filter_horizontal = ('collections',)

admin.site.register(Collection, CollectionAdmin)

which casues error : <class 'store.admin.CollectionAdmin'>: (admin.E019) The value of 'filter_horizontal[0]' refers to 'collections', which is not a field of 'store.Collection'. I would really appreciate your help.

The model on which the admin acts is the Collection model, so the field is product:

class CollectionAdmin(admin.ModelAdmin):
    filter_horizontal = ('product',)

Note: Since a ManyToManyField refers to a collection of elements, ManyToManyFields are normally given a plural name. You thus might want to consider renaming product to products.