Here's a Tweet from CashU with more info:

🤫 Don't tell anyone but the "even if you don't have a Cashu wallet" part is a lie because that page is actually a Cashu wallet (just with very limited abilities).

https://twitter.com/CashuBTC/status/1633775217699966977 [Nitter]

Source:

cashu-redeem https://github.com/cashubtc/cashu-redeem