You can accept file uploads directly on your scheduling page by adding a Custom Question with the type Attachment.
Create a new link or edit an existing link.
Click Next twice to navigate to Step 3 of the wizard.
Click the Add button next to Custom Questions.
In the Edit Form dialog click the Add new question button.
Select the Attachment question type.
Type in the Question text. You can also type in Help Text to provide your invitees with detailed instructions on which file to upload. If they need to download a file before uploading, for example to sign a document, you can type the download URL in this field and it will automatically be hyperlinked.
Click Apply then Save your link.