Why the starting weights are light

The starting weights are light on purpose. Your body must get used to the Squat frequency so you don't get sore, skip workouts and plateau early on.

The app asks you for your best lifts when you install it the first time. It will then make you start with about 50% of what you can do for 5 reps. If you never did the exercises, it will make you start with the empty bar.

You can start heavier if you want by tapping the weight your next workout. You can also increase the increments from 2.5kg/5lb to 5kg/10lb. But don't be greedy or you'll get sore, skip workouts and plateau early on.

It's much better to start on the lighter side as the app recommends. Let it be light if it's light. The app will increase the weight each workout anyway, things will get heavy within a few weeks. Focus on form meanwhile.

Be the turtle, not the hare.

Read also the website

https://stronglifts.com/5x5/#Starting_Weights
https://stronglifts.com/5x5/#Starting_Too_Heavy