Seemed more appropriate to respond to you in this thread.
Originally Posted by pfavayi
I cannot install firmware from this official site through TWRP, it always says there's a problem with the zip file.
I just boot into recovery and select the zip file during install.
I have downloaded the file many times but I still get the same problem.
Do I need a special program or a special process to install this file?
Should be nothing special.
My first thought was you are running into a zip Signature problem.
I just got a chance to try the 9.5.30 version from your link.
Selecting Poco I was redirected to github and downloaded it from there.
First install no problems.
I turned on Zip signature verification on under setting in twrp and tried again.
I assume this error you are seeing.
Not sure what recovery you are using but, you should be able to turn off the signature verification.
I did not check the zip but, either it's not signed or not signed by a generic key.
I do not normally use the flashable firmware updates.
I follow the updater on telegram though. I prefer the fastboot links.