In order to connect Hubdoc with Xero Files, you must first connect Hubdoc with Xero. Instructions for how to connect Hubdox with your Xero account are located here.
Since you have previously connected Hubdoc with Xero, you can now select Xero Files as a destination.
To do this:
1. Login to Hubdoc
2. Click on the Gear Icon in the top, right corner
3. Navigate to the Integrations tab
4. Check the box that says Push to Xero Files
5. Navigate to Manage Accounts tab
6. Select the account which you want to push to Xero Files. In the example below, we have selected Grasshopper
7. Click on the blue triangle to the left of the individual account
8. Click on the Autosync to Xero Files check box
9. Select 'Save'