Hello,
I think you can use the image for your phone, it is a Generic System Image, i.e. it is not for a specific phone, but for all phones that can handle GSI/Treble. See also the table. Device support (Project Treble)
You will have a super partition just like my Note 9pro, or did your phone come out of the factory with Android 9?
So you could also follow the instructions I posted. The important thing is that if you want to root it, get a recovery.img, which you can copy out of the original image file from Xiaomi (after unzipping it, you will find a folder with “Recovery”, there is the image file inside). Save this in any case, because with TWRP there were still problems regarding super partition. Therefore I had to switch again and again to the original Recovery.
Addendum: You need, if you want to use this GSI file, the …arm64_bvS.img.xz file.
Unzip it first and follow the instructions.