Permalink is the custom URL structure for your website. After installing WP Crowdfunding, you must use Post Name. Because the dashboard URL and other dependent links are set up based on the slug that you choose.

To set up the correct permalink type for your WordPress website, go to 

wp-admin (WordPress Dashboard) → Settings → Permalinks

If you have set anything other than Post Name, then there is a very high chance of your visitors getting a 404 error on the frontend section of your website.