Below are are most common reason and solution for this problem:
1.) Update Woocommerce & Knawat Dropshipping plugin to latest version.
2.) API keys are inserted and Valid.
3.) Products are add to store at app.knawat.com if already added than do sync.
4.) WP_CRON is must needed enabled.
==> Our plugin use WP Cron for syncronize products and Orders into background, so please confirm its not disabled on your website
5.) Port 80 and 443 should be open.
==> Port 80 and 443 is must needed Open for Knawat Dropshipping plugin get working. this ports are open on all hosting but because some reason its get closed on some shared hosting. so, please check if port 80 OR 443 close on your web host then please contact your hostingprovider for open it for you.