According to the site, I understand weekly update is better to use twrp. I'm not sure but there was two exceptional devices. But in general, you go into twrp recovery then choose to install zip.
Oh.. Sorry. You have done it.... Hum.....
Have you download correct rom file?
And the guide says For Xiaomi MiPAD 1 is required to merge both system partitions by this guide
Did you do that too?
Then I'm no more help to you.. Sorry.