Do I need a special stand or tripod?

A sturdy phone holder or even a DIY stack setup can work - just make sure it can place your phone between 6 to 12 inches / 15 - 30 cm off the ground.

Any higher and it will impact overall accuracy or not be able to see the ball.

A steady tripod is definitely the best option to keep results consistent and accurate.

Here are some recommended tripods from Amazon:

Ulanzi MT-84 Phone Tripod — $24.95 — View on Amazon

NEEWER Entry Level Version Mini Tripod — $13.49 — View on Amazon