Error flashing - "Error 7" and/or "Can not find META-iNF"

Hey guys,

so I did the OTA update to 6.0 the other day and it completely ruined my battery life so I decided to go back to 5.1
I unlocked the bootloader through fastboot and then install TWRP also through fastboot. After wiping everything, I downloaded a ROM, moved it to my One and tried to install it how ever I always get either "Error 7" or "Could no find META-INF"
I have tried 3 different ROMS, admitedly all CM13 but they all give me either one of those errors.

Anyone have any idea how I can possibly fix this?
Currently there is no OS on my One.
Thank you!

Download from this link

can't find update

hii guys
i try to update my galaxy s5 G900a
but i can't get an update Cpa2 or cpa3
my baseband cpa1
location indonesia ... any way for me to update ?

Download from this link

Floating call window (cant find setting in s7)

I think I am probably just being thick here as I am sure I had it enabled.

On my S5 I had a floating window whilst in calls that I could interact with (drag it around the screen, mute etc)

I can't for the life of me work out how to enable this on the S7? I have played with notification settings all sorts is it just not available? or am I simply being thick?

Download from this link

Cant find a straight answer is 510 serial safe from bootloop

No one can answer this. All of you that have had 510 serials please give feedback

Download from this link