Zoho NOTEBOOK: What are file size restrictions?

I understand that Zoho NOTEBOOK is a free product, and what it offers is great. But I'm wondering what the file size restrictions are.

When I record an audio note in Zoho Notebook, what is the maximum length of recording time/audio file size?
When I wish to upload MP4 video, what is the maximum video size I can upload per Zoho Notebook restriction?

Moreover, does Zoho Notebook use its own storage structure, or can I upgrade my storage for Zoho Notebook to add larger file attachments, videos and audio notes?

For example, like Evernote. Basic file storage has limits but if you wish to upload bigger files, it's possibly by upgrading. Is this possible on the Zoho Notebook product?

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