I downloaded the following three modules, put them in the "/odoo/custom/addons" folder in Ubuntu server, and unzipped all of them. But I can not find any of them in the app tab in my cloud-based odoo v13. I have turned on the developer mode. Could anyone help me with this problem? Thanks.
https://apps.odoo.com/apps/modules/13.0/purchase_order_line_packaging_qty/
https://apps.odoo.com/apps/modules/13.0/sale_order_line_packaging_qty/
https://apps.odoo.com/apps/modules/13.0/packaging_uom/#id5
I find another tricky thing. Some addons may block some other addons. For instance, if I install both "packaging_uom" and "app_odoo_customize", then "app_odoo_customize" will not be displayed. After I uninstall "packaging_uom", then I can find "app_odoo_customize" in App. I spent a lot of time to figure this out, so want to share it here in case it will be helpful to someone else.