It is possible to let users leave reviews without registering on that site.
First, go to WordPress admin > WooCommerce > Settings > click on the Products tab at the top.
In the reviews section there, make sure the option to enable reviews is selected:
Make sure that “Reviews can only be left by “verified owners” is not checked.
After that in your WordPress dashboard, go to Settings > Discussion and make sure the option requiring users to be logged in to make a comment is disabled.