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 the word 'Accounts' in the top, right corner
3. Navigate to the 'Destinations' 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 'Send to Xero Files' check box
9. Select 'Save'