You can find the mounting instructions in the QSG (Quick Setup Guide) on the support portal here including how to attach on a flat surface, to a pole, how to earth grounding, etc.
You can check the radiation pattern here. Or you can also see the Azimuth and Elevation Antenna Patterns of T310c in the datasheet here. Those figures 2-5 applied to T310c as well. It is omni directional antenna.
@Tony Heung The Knowledge Base article with radiation patterns is a great resource, Thank you very much for sharing the link! Will the article be augmented with 11ax/Wi-Fi 6 AP patterns? At the moment only R750 is there.