Asus ZenFone 3 Max and DualShock 4 - Can pair, but doesn't do anything

I bought and downloaded GTA: San Andreas on my phone. I had intended to pair my DualShock 4 to my phone, as seen here and as discussed here . However, while I can pair the controller, it doesn't do anything, either in-game, or on the home screen. The controller works, since I can pair it up to my laptop and play games on it, and it's got a full charge (for good measure, I used my phone's OTG and connected it wired; didn't work either). The phone being shown on the vids is the ZenFone 3, which is the more premium brother to my ZenFone 3 Max 5.5. Is there anything I can do to make the controller work? Why isn't it working in the first place?