You must use your pickpocket skill on your mother's Cloak of Shopping, retrieve the Rectangle of Potentia. Carefully enter the Sacred Digits into the Portal of Reclamation to receive your reward.

Go carefully young adventurers, for the penalty for failure is great, and La Chancla is indeed fierce.

When I went on the main Genshin subreddit, I was so baffled that people do little pulling rituals, and even do parties with thematic food and decoration for characters to influence their gacha luck 😵‍💫 Maybe they didn't take it that seriously, but it still felt like a very unhealthy attitude towards such a predatory game.