一组用于共享和管理内容、知识和应用程序的 Microsoft 产品和技术。
Dear Ethan YANG1,
Thank you for providing the necessary information about the issue you are facing.
For your first issue you have to enable external sharing to share files with anyone link.
Please go to SharePoint admin center >> policies >> sharing >> set to anyone
To change the external sharing setting:
- Go to Active sites in the new SharePoint admin center, and sign in with an account that has admin permissions for your organization.
- In the left column, select a site. (For a channel site, select the link in the Channel sites column and then select the site.)
- On the Settings tab, select More sharing settings.
- Select an external sharing option (see the table in the next section).
For your second question YES if you share SharePoint site the user required to logging to Microsoft account this is expected behavior.
As a workaround we suggest you to crate a gust account to the user in your tenant. click here to learn how to crate a gust user --->> Guests in the Microsoft 365 admin center
To learn more about sharing settings in SharePoint OneDrive click here---->>Manage sharing settings for SharePoint and OneDrive in Microsoft 365 - SharePoint in Microsoft 365 | Microsoft Learn
I hope this helps If you have any additional questions or if you need any additional help regarding this or anything else at all - let me know, I'll be here to help you out.
And in the meantime, I hope you'll have a lovely day ahead, stay safe & take care!
Yours sincerely,