Box Files is a bundle created by Box Bundler = ID - 28044 which makes sharing, storing, access and management of all of files online within NetSuite easier. The Box Files bundle contains three scripts that are deployed on records and due to which a "Box Files" sub tab will show up on records. The script by default has audience set to all Roles and Employees. So what will happen is if you give your Vendor access, when the vendor logs in he would not see the "Box Files" tab under any records and in turn will not be able to use the functionality provided by it which would have made it easier for the Vendor to share and store data with you. In order for all the entities to have the option of using Box Files follow the steps below :
Note: The following steps assumes users have already installed the bundle (Customization > SuiteBundler > Search & Install Bundles)
1. Navigate to Customization > Scripting > Scripts > edit Box Files Suitelet
2. Click Deployments tab.
3. Click Box Files Suitelet.
4. Click Edit.
5. Under the Audience tab > GROUP box > select the Vendor group.
Note: Users need to create a vendor group (Lists > Relationships > Groups) when there is no VENDOR box in the Audience tab.
After this Box Files tab will show up for everyone who has access.