While importing catalog in commerce server, if you are facing access denied error, please check following

1. Have sufficient permission in SQL Server for the Application pool identity (under which the Catalog Web Service is running)

Following DB permissions are required for the Application Pool Identity (under which the Catalog Web Service is running)

 

Database Name

Roles

MSCS_Admin

admin_reader_role

 

MSCS_CatalogScratch

db_datareader, db_datawriter, db_ddladmin

<SiteName>_ProductCatalog

ctlg_CatalogWriterRole, db_datareader, db_datawriter, db_ddladmin, db_securityadmin, Inventory_ReaderRole, Inventory_WriterRole

2. The Application Pool Identity (under which the Catalog Web Service is running) user has Read, Execute and Write permission on the CatalogAuthorizationStore.xml

3. The Application Pool Identity (under which the Catalog Web Service is running) user access on Windows Temp directory

4. The Application Pool Identity (under which the Catalog Web Service is running) user access on ASP.net temporary files directory