download HEVC/H265 codec

K-Lite Codec Pack Mega is the most powerful media player in the world. (Its player is actually MPC-HC)
If you still can't play it after installing and using KLCP, your hardware is the problem as the file is quite heavy to decode and play.

That's quite enough only if that Core i5 is the 6th gen or newer while assuming there is no dedicated graphics card available (Note that only the 7th gen and newer have native support for HEVC 10-bit decoding). Anything less than that results in high CPU usage (> 85% (and don't forget it's going to run for about 2 hours)) due to software (not hardware) decoding and laggy playback.
The minimum GPU requirement for smooth playback of 4k HEVC 10-bit HDR is Nvidia GeForce GTX 1050. One needs either an HEVC 10-bit capable CPU or a capable GPU.
FYI software decoding of H.265/HEVC can be done via both CPU and GPU.

Remember that you have another great choice i.e. AMD Ryzen 5 series processors. For example AMD Ryzen 5 2600X (around $200) has beaten Intel Core i5-7600K (about $250) in many performance tests.

Don't forget that your display (Monitor or TV) should be UHD HDR capable.

                                       "It's hardware that makes a machine fast. It's software that makes a fast machine slow."

Is that a laptop class Core i5? I don't recall any desktop i5s which clock that low (except for the 1st gen i5s).
If so, I'd expect it to struggle with this.
MeH already gave a lot of info. If you're looking for an ultra cheap solution, there's a number of cheap TV boxes which should be able to do the trick. The downside being that they probably don't do terribly well for when you need software decoding (e.g. 10-bit H.264) and don't have the flexibility of a computer.