In order to sweep from a paper wallet, you will need to be using a Multisig Shield wallet in Blockstream Green.
Mobile
1.
Log in to your Multisig Shield wallet and tap Receive.
2.
Select More Options then tap Sweep From Paper Wallet.
3.
Paste or scan a private key, then the amount will automatically populate. Select your desired fee and tap Next.
4.
Review the transaction and select Send. The swept amount will then appear in your Green wallet.