This issue can happen due to different factors.

1. The .htaccess file hasn't been renamed to .hataccess from default htaccess name that may come with the zipped package. Please follow the instruction manual to try renaming the file again. Usually located in the root directory of the script.

2. The .htaccess file may not contain the same codes as the zip file has when you've unpacked the zip file. In this case, open the ".htaccess" or "htaccess" file from the zipped file in a notepad or any other text editor. Then copy the contents of the file. Then open the .htaccess file in your server where you've uploaded and then paste all the codes by overwriting any existing. Once pasted then save the file and re-fresh the browser.

3. Refer to the minimum server requirements for the script by going to https://snetworksclassifieds.com/?page=requirements and make sure it meets all of them.

4. Check your PHP version, if your server is using PHP 7 then switch your cPanel's PHP version from 7.x to 5.x. (most commonly caused).

If the problem still doesn't resolves then login to your account in SNetworks and open support ticket requesting for assistance.