I’ll introduce recommended settings for G Suite’s “Whitelisted Domains” and “Google Drive Sharing Settings”.

Prerequisites

• "Restrict sharing with domains not on whitelist" is configured
• External organization domain to share with: example.com

Google Drive Sharing Settings

This assumes “Restrict sharing with domains not on whitelist” is configured.

? Reference: ドライブ ユーザーの共有権限を設定する - G Suite 管理者 ヘルプ

Whitelisted Domains

This assumes that the external organization domain example.com that we want to add to the shared drive is not registered in the G Suite Admin Console “Whitelisted Domains”.

Steps to Add External Organization Domain to Shared Drive

Domains Not on Whitelist Result in Error

If you haven’t registered external organization domains to the whitelist, you’ll get an error message like the following and won’t be able to add them to the shared drive:

target@example.com はホワイトリストに登録されているドメイン内の Google アカウントではないため、このアカウントとアイテムを共有することは ◯◯ の管理者が設定したポリシーにより禁止されています。

Registering Domain to Whitelist

In the G Suite Admin Console “Whitelisted Domains”, register the external organization domain example.com that you want to share Google Drive with to the whitelist.

Share with Members Outside Organization?

A warning message “Share with members outside organization?” will be displayed, but you’ll now be able to add them to the shared drive.

That’s all about wanting to properly configure G Suite’s “Whitelisted Domains” and “Google Drive Sharing Settings” from the Gemba.