If you use the new product catalog, every user has full access to it. You can configure access permissions to the product catalog only if you're using the old product details form. If you have problems with using the new catalog, you can always switch to the old one. Go to the Online Store section > Settings > Online Store Parameters.
Go to the Product catalog tab > disable the Enable new product details form.
Bitrix24 CRM Access Permissions, available under CRM > Settings > Permissions, do not currently allow to configure users access to the product catalog. By default, only Bitrix24 account administrator can add products to the catalog. Here is how to give the ability to add products to the catalog to other account users:
1. Open CRM > Settings > Permissions > Access Permissions.
2. Access can be given to the role. Choose role and open it for editing.
3. Activate option "User can edit settings".
Important: this option activation not only opens access to product catalog, but also gives the ability to edit other CRM settings.