To use this feature Outbank and Docutain have tobe installed on the same device.
Download the iOS Docutain App: https://apps.apple.com/de/app/docutain-scan-pdf-ocr-qr/id1416707024
Download the Android Docutain App: https://play.google.com/store/apps/details?id=com.infosoft.docutain

And this is how it works:

Link a transaction / contract with an existing document from Docutain: 

1. Select the transaction / contract in Outbank you want to link with a document from Docutain.
2. Click on 'Connect Document' in the transaction or contract details. Docutain will be opened.
3. Login in Docutain and select the document you want to link.
4. Outbank opens again after you selected the document. After the Login in Outbank the transaction / contract details with the link to Docutain will be opened.

The document does not yet exist in Docutain?

1. If the document does not exist in Docutain please scan the document and save it in Docutain. 
2. Then select the document you want to link with a transaction or contract in Outbank and tap on the three dots in the upper right corner. Select 'Link sales / contracts (Outbank)'. Outbank opens automatically.
3. Login in Outbank and choose if you want to link the document with a transaction or a contract.
4. Search for the transaction / contract and tap on 'Connect' in the upper right corner.
   
   

To open a document from Outbank, just search or the transaction or contract and open the transaction / contract details. Then tap on 'Open in Docutain'.

If you want to delete a link in Outbank just swipe left over the Docutain cell in the transaction / contract details and select 'Delete'.

This feature is available from version 2.41.0 for iOS and Android. Docutain is currently not available for macOS.