I've tried to install the following module https://www.odoo.com/apps/modules/9.0/product_multi_category/ to my existing Odoo 9.0 to enable multiple categorization for products.
But couldn't find instruction to install or enabling the module.
So far I did is downloaded the module for Odoo 9.0 series. extract it into my [odoo_path]/addons/ directory. And also set file owner and group to "odoo", which is my system user for Odoo ERP 9.0. I'm using linux.
Any advice or reference would be appreciated, Thanks.