I know this was asked long back, but still I believe many people are searching for the way to do it.

Please check Box SDK for more details.

And I'm using OAuth2.0 - Custom App. You can create the credentials from the developer console.

Here's the code.

from boxsdk import OAuth2, Client
#from boxsdk import Folder

auth = OAuth2(
    client_id='fbxxxxxxxxxxxxxxxxxxxxxxxxxxxxx9',
    client_secret='bPxxxxxxxxxxxxxxxxxxxxxxxxx4Or',
    access_token='QExxxxxxxxxxxxxxxxxxxxxxxxxxwt',
)
client = Client(auth)

root_folder = client.root_folder().get()

items = root_folder.get_items()
for item in items:
    print('{0} {1} is named "{2}"'.format(item.type.capitalize(), item.id, item.name))
    with open(item.name, 'wb') as open_file:
        client.file(item.id).download_to(open_file)
        open_file.close()

Hope this will help you. Thanks to the Python boxsdk 2.0.0 Doc.

It looks like we're experiencing a minor bug on our end that's preventing downloads. If you use 'https://www.box.com/' instead of 'https://api.box.com/' the download should work. We're working on fixing the bug right now, however!

Get metadata of shared Box link:

shared_folder = client.get_shared_item("https://app.box.com/s/0123456789abcdef0123456789abcdef")

Loop through each item inside the folder and download each file using boxsdk.object.file.File.content or boxsdk.object.file.File.download_to:

for item in shared_folder.get_items(limit=1000):
    if item.type == 'file':
        # Get file contents into memory
        file_contents = client.file(file_id=item.id).content()
        # Or download to file
        client.file(file_id=item.id).download_to(item.name)