You have to login to the back-end of the site  http://your_wordpress_site_url/wp-admin.

For CMS2CMS preview site use login: testuser , password: testuser.

If you migrated to your site, use your own access credentials.

Follow this list to check results:

  1. Content pages
  2. Menus
  3. Images
  4. Categories
  5. Users

Content pages

Content pages in WordPress

Menus in WordPress

Images

Images in WordPress

Categories

Categories in WordPress

Users

Users in WordPress

When everything is checked, complete your migration and transfer all the data.