According to xda-developers.com the Unofficial TWRP works only for Redmi Note 9 (merlin) without NFC support. If your device is the NFC version you can not use this TWRP.
Furthermore it is necessary to disable AVB before doing any modifications. The flashing instructions are incomplete. Before flashing magisk_patched.img or twrp.img make sure to flash "...
Need to narrow it down a bit, potentially three items assuming that your phone network operator is not at fault
Can you if possible try your phone and cable on a different PC.
Do you have any data transfer issues with the phone on the PC ? such as backups etc, worth trying another cable if possible.
Daft one but try the cable ...