It's P2PK locked to your NPUB, so you will either have to import your nsec into your Cashu.me wallet to redeem there, or redeem using Nostrly Cashu Redeem using a signString() compatible NIP-07 signer like Alby or AKA Profiles.

https://www.nostrly.com/cashu-redeem/

Here's a video showing how to lock and redeem in Cashu.me:

https://m.primal.net/PhwX.mp4