TWRP Updated version for SM-G530T1?
You seem to have downloaded the wrong ROM, if you are 100% sure this is the correct rom it might be a bug in TWRP.

You could possibly try to reinstall TWRP like this:


Download latest TWRP for your device (you already have)
Copy it to phone via OTG or SD-card
Select 'install' in your current TWRP
Select 'image' option
Choose the TWRP image file
Select the type 'RECOVERY' when prompted, and flash it.
Power off from recovery and boot it into recovery again and try to flash the ROM again.


Another thing you can try is wiping:


Boot your device into recovery mode
Select 'advanced wipe'
Check 'cache', 'dalvik cache', and 'data'
Wipe


Then after wiping try flashing the ROM again.