Install Google Play Store on ROM without Google apps I rooted my Samsung Galaxy S3 and flashed SlimKat's 4.4 ROM and it has no Google Play. When I downloaded GAPPS, it says "Cannot open file" when attempting to open.

How can I install the gapps.zip?
To install gapps, flash them from the recovery (the same way you installed the ROM), you shouldn't open the .zip file since it is automatically processed by the recovery.