When you are installing the extension, you go to admin >> extensions >> installer and click the upload button and select the extension ocmod.zip file but you got the following error like "The directory catalog/controller/product is not allowed to be written to – Opencart error". The way to solve it is to add the path at admin\controller\marketplace\install.php
Here in the example, the path is catalog/controller/product/ so we needed to add at
// A list of allowed directories to be written to $allowed = array( 'admin/controller/extension/', 'admin/language/', 'admin/model/extension/', 'admin/view/image/', 'admin/view/javascript/', 'admin/view/stylesheet/', 'admin/view/template/extension/', 'catalog/controller/extension/', 'catalog/language/', 'catalog/model/extension/', 'catalog/view/javascript/', 'catalog/view/theme/', 'system/config/', 'system/library/', 'image/catalog/', 'catalog/controller/product/' );
Whatever error path you get, you need to add here to install successfully. But the best practice is to stick to the provided folders only if you need to manage multiple folders than manage subfolders within them.
Thanks
Rupak Nepali