I don't installed the twrp.
I used the Instruction here
https://xiaomi.eu/community/threads/guide-a-beginners-guide-to-flashing-xiaomi-eu-stable-on-mi-10t-mi-10t-pro-redmi-k30s-ultra-thorough-step-by-step.61742/
Here is written only to Boot the Recovery and not to Install.
Edit: i found the...