Attachments of emails get picked up automatically and shown in "Accounts" > "Files".

To upload files manually, just click on the blue 'Add a File' button in the Files tab under the appropriate account. 😀
Attachments of emails get picked up automatically and shown in "Accounts" > "Files".
To upload files manually, just click on the blue 'Add a File' button in the Files tab under the appropriate account. 😀