To use a Thunderbolt 3 adapter to output to a display at 60Hz, your monitor must support the refresh rate and you need to set the monitor to work at 60Hz. By default, most monitors are set to DP1.1, which will not work with this Thunderbolt 3 device when you use a display at 60Hz. In most cases, you need to set your monitor's DisplayPort settings to DP1.2.
To resolve this issue, use the buttons on your monitor to change the DisplayPort settings to DP1.2. For more information about changing your monitor settings, refer to the website of the manufacturer of your monitor.