You can either upload large files directly, or use the file sharing service of your choice. Our file upload panel now includes support for Dropbox & Google Drive so you can seamlessly transfer links to your cloud files right within your AirGigs message thread or order page.

WeTransfer is also a popular and free upload method that doesn't require you to create an account. If you use WeTranfer please use the "File" method that generates a download link to your file, and doesn't require another user's email address

WeTransfer
https://wetransfer.zendesk.com/hc/en-us/articles/210064643-Email-versus-Link-transfers 

WeTransfer Share Link

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Dropbox
https://www.dropbox.com/en/help/167 

Dropbox Share Link;