In regard to your questions:
1. How can I download multiple files/ folders from OneDrive?
A: The ability to download an entire folder in the OneDrive for Business is not enabled yet, we can only download single files. About your requirement, we suggest you vote the following feedback in the Uservoice. Understanding your experience helps us to make our product and service better for you and others.
https://onedrive.uservoice.com/forums/262982-onedrive/suggestions/11158533-download-folders
As a workaround, to use the folder on the local, you can consider using OneDrive for Business sync client or Open with Explorer feature:
Get started with the OneDrive for Business Next Generation Sync Client in Windows
How to use the 'Open with Explorer' command to troubleshoot issues in SharePoint Online
2. If someone has shared a folder with me, how can I sync it to the OneDrive Business Sync Client on my desktop?
A: We can only see the shared folders in the Shared with Me section. it’s not feasible to sync the folders in the Shared with Me section currently. About this feature, we welcome and encourage you to share your ideas through User Voice forum. Understanding your experience helps us to make our product and service better for you and others.
https://onedrive.uservoice.com/forums/262982-onedrive/suggestions/15474660-sync-shared-folders
In addition, this shared folder sync feature is in development, you can follow up on Office 365 roadmap for the latest updates:
We appreciate your understanding.
Kerwin
Open Your Onedrive Folder
The following instructions demonstrate the process of setting up OneDrive for Business as a traditional file folder in Windows. Download: If you do not have Office 2013 installed on your computer (OneDrive is included in the software package), you can download the OneDrive for Business application from Microsoft's OneDrive download page. Posts, Downloads & Events. How to Selectively Sync Folders to OneDrive for Business. Just be aware of the limitation that you can only sync 20,000 items (which includes files and folders) from your OneDrive for Business library, or 5,000 items (files + folders) from team site libraries. But the feature isn’t enabled by default and for the time being is only supported for eligible OneDrive for Business users. KFM differs from Folder Redirection in that it migrates files to the.