Pagination not working. No errors when compiling.

posts.njk

---
layout: layouts/allposts.njk
permalink: '/posts{% if pagination.pageNumber > 0 %}/page/{{ pagination.pageNumber }}{% endif %}/index.html'
title: My Posts
pagination:
  data: collections.posts
  size: 3
  reverse: true
---

{% set postslist = collections.posts %}
{%  include "postslist.njk" %}

postslist.njk

    <!-- blog post content -->
    <section class="blog-content">
        <div class="main-heading">
            <h1 class="font-mont h1-style">BLOGS</h1>
        </div>
        
        <ol class="blogs">
            {% for post in postslist %}
            <!-- blog posts -->
            <li class="blog-container">
                <div>
                    <a href="{{ post.url | url}}">
                        <img src="{{post.data.featuredImage}}" alt="blogs" />
                    </a>
                    <div class="blog-heading">
                        <div>
                            <a href="{{post.url | url}}">
                                <p class="p-style">{{post.data.title}}</p>
                            </a>
                            <p>{{post.data.tag}}</p>
                        </div>
                        <div>
                            <img src="/images/link pointer.svg" alt="link" class="link" />
                        </div>
                    </div>
                </div>
            </li>
            {% endfor %}
        </ol>
        <ol>
    <li>{% if pagination.href.previous %}<a href="{{ pagination.href.previous }}">Previous</a>{% else %}Previous{% endif %}</li>
{%- for pageEntry in pagination.pages %}
    <li><a href="{{ pagination.hrefs[ loop.index0 ] }}"{% if page.url == pagination.hrefs[ loop.index0 ] %} aria-current="page"{% endif %}>Page {{ loop.index }}</a></li>
{%- endfor %}
    <li>{% if pagination.href.next %}<a href="{{ pagination.href.next }}">Next</a>{% else %}Next{% endif %}</li>
  </ol>
    </section>

when I changed the value of size to 4 i got the following error
Problem writing Eleventy templates: (more in DEBUG output)

Output conflict: multiple input files are writing to _site/posts/index.html. Use distinct permalink values to resolve this conflict.

1. ./posts.njk
2. ./posts.njk
   DuplicatePermalinkOutputError was thrown:
   (Repeated output has been truncated…)

After changing the permalink, I am not getting any error but pagination is not working.
file structure after permalink was added:
posts/page/1

all the blog posts are added to 1 and there is no new file where other posts after pagination is added.