Use UserInputService! You use UserInput service to get input from the gamepad (controller). You would then have to create your own script to enable movement and camera manipulation. I'm actually working on this myself. Until I perfect my script for public use, you can use the wiki tutorial (here)[http://wiki.roblox.com/index.php?title=Gamepad_input]. I'm sorry that I have to give you a wiki link, but there's so much to this so I have to give you a wiki link.
To make your game available to be played on Xbox, please do the following on a computer: Navigate to your game's page. Click the Menu button in the upper-right corner of the game's page that looks like 3 dots aligned horizontally. Click Configure this Place in the menu that appears. Click the Access tab on the left. Pair an Xbox One wireless controller with your Mac. Turn the Xbox controller on. Press and hold the Pairing button on the top edge of the controller until the Xbox logo blinks rapidly. Playing an Xbox game. With a Ps5 controller. 16' MacBook Pro 2019. Playing an Xbox game.
Use a Micro-USB cable to connect the PS4 controller to your Mac. Press the PlayStation button in the middle of the gamepad (to turn it on). Choose Apple About this Mac. Click System Report. Of the game controllers available for home computers, only a few are officially supported on the Mac, but you can often get others, like those for the PS3, Wii, or Xbox, working just fine.
Tips for making your game good with controllers:
How To Play Roblox On Mac With Xbox Controller
-I'm working on GTA controls. By that, I mean the camera acts like it does if you're playing GTA 5. You can set it wile standing still, and it will smoothly move back to its original position when your character moves again. Also, the camera will be able to turn the character, allowing for more precise movement
-Get creative with binds. I'm working on using the bumper buttons on the controller to select a tool, L3 (press left stick) to sprint, B to crouch, and other controls.
-Make sure the binds are good so that you can easily maneuver your fingers to the right buttons. Sort of like the last tip, but this is important enough to be its own tip.
Controls For Roblox On Xbox
-Use ContextActionService (I haven't proven CAS to work with controllers yet, but you can test it, I'm sure it works just fine) to bind controller buttons to keyboard and mouse keys. I'm going to bind R3 to mouse button 3, B to ctrl, Y to the inventory key (haven't yet decided what key I want to open the inventory).
Roblox Games With Controller Support
Again, I apologize that I couldn't give you a full tutorial. There would be too much in this answer. However, if you need any help with it, please comment, and I'll help you as soon as I can. Thanks!
Extra note: Getting your controller set up on your computer may be difficult. I couldn't get my Xbox 360 controller set up, so I just used a PS3 controller. You may want to choose what I did if you can't get your controller set up on your PC.