Hi,
Similar issue for me. Installed this plugin, activated. Latest WooCommerce and all up to date. WP 6.6.1 with back-end at Flywheel. So it should not be a WP or server issue.
Select Add a Supplier and enter data, hit Submit and get a 404 page not found error. Supplier is not saved.
Try looking at Inventory page and I get the “There has been a critical error on this website. Please check your site admin email inbox for instructions.” …..
The plugin sounds like it would be very useful, but this is just time wasting.
Tony