Macbook pro mid 2015 and BenQ BL2711U 4k 60hz

Hi.

I have macbook pro mid2015 and i would like to connect it with BenQ BL2711U display and use it with 4k and 60hz.

I read your article (https://support.apple.com/en-gb/HT206587).

And you says «These computers also support 60Hz refresh rate over HDMI when used with a supported HDMI 2.0 display, HDMI Premium Certified cable, and a compatible third-party USB-C to HDMI 2.0 adapter.»

But i have hdmi 2.0 and it still 30hz.

Than i read that «With macOS Sierra, MacBook (2015 and later) supports 4K (3840 x 2160) displays at 60Hz over DisplayPort.»

So, what do i need? hdmi 2.0 or displayport?

Can you give me advice, please.

Thanks.