Many apps want the server to to have the ability to export the private key for a user’s wallet. This can be used to self-host a recovery site where users can export their private key outside of your core application. To enable this, Privy generally recommends:
1

Create a wallet with a 1-of-k key quorum

Create your wallet with a 1-of-k key quorum, whose members include at least a user and an authorization key controlled by your server. You can do this via Privy’s REST API.
2

Export the wallet from your server

As a satisfying member of the key quorum that owns the wallet, your server’s authorization key can unilaterally export the wallet. Follow this guide to export the private key for your user’s wallet from the server.