Getting error in Laravel 5.7 edit route page not found

Laravel Version 5.7 PHP 7+

I created a resource controller -> CategoryController [having all the magic methods]

This is the routes/web.php

Route::group(['as'=>'admin.','middleware'=>['auth','admin'],'prefix'=>'admin'], function(){
    Route::get('/dashboard','AdminController@dashboard')->name('dashboard');

    // product resource controller methods
    // check php artisan r:l
    Route::resource('product', 'ProductController');
    Route::resource('category', 'CategoryController');

    Route::resource('profile', 'ProfileController');
    Route::post('remove', 'CategoryController@remove')->name('category.remove');
});

---

Now as you can see, I have "http://127.0.0.1:8000/admin/category/1/edit" for one of my categories to edit with category id = 1, that is also stored in the database.

<?php

namespace App\Http\Controllers;

use App\Category;
use Illuminate\Http\Request;

class CategoryController extends Controller
{
    public function index()
    {
        $categories = Category::paginate(3);
        return view('admin.categories.index',compact('categories'));
    }
    
    public function edit(Category $category)
    {
        return "This is category edit page";
        // dd($category);
        //  $categories = Category::where('id','!=', $category->id)->get();
        // //  dd($categories);
        // return "This is category edit page";
        //  return view('admin.categories.create',['categories' => $categories, 'category'=>$category]);
    }

When I try to go to this edit category page, it shows 404 page not found error.

Although, when I made an individual route for edit method with a closure function to return some text, it worked perfectly.

    Route::get('category/{category}/edit', function($category){
        return $category;
    })->name('category.edit');

PLEASE HELP

via Chebli Mohamed