The Destination Tag is required when sending any XRP from an external address to your Uphold wallet.
When you’re creating the transaction, make sure that you insert it in the Destination Tag field. (Some platforms label this field memo “Memo”)
Here’s how you can find your Destination Tag:
1 - Tap 
if you’re using the app or go to the Anything to Anything pane if you’re using your browser.
2 - Select From.
3 - Go to ‘Crypto networks’ and choose XRP.
4 - Select the destination wallet above the QR code (if you have more than one).
5 - Below the wallet address you’ll find the Destination Tag for the chosen destination wallet.