Could be something to do with .htaccess file. Please google “WooCommerce API 403 Forbidden error”.
These articles may be helpful:
https://www.cloudways.com/blog/fix-403-forbidden-error-in-wordpress/
https://github.com/woocommerce/woocommerce/issues/6529
https://github.com/WP-API/Basic-Auth/issues/21
Also, do you have SSL (https) enabled on your website? If not, try to install it.