To download folders in Tencent Cloud Object Storage (COS), you can use the COSBrowser tool or SDKs. COSBrowser allows you to manage your COS resources through a graphical interface. When you want to download a folder, you can select the folder in COSBrowser, then click the "Download" button, and it will package and download the folder and its contents to your local machine.
Additionally, if you prefer using programming methods, you can utilize the COS SDKs provided by Tencent Cloud. For example, with the COS SDK for Python, you can write a script to list all the objects within a folder and then download each object one by one to your local directory, effectively downloading the entire folder structure.
For more advanced needs, such as synchronizing folders or large-scale data transfers, you might consider using Tencent Cloud's Data Transmission Service (DTS) or other related services that offer more efficient data migration and synchronization capabilities.