The door opened to the desired angle I need, but it can still be push to open more

• This is because when you were installing the arm, the spindle did not fully open to hard stop.

Step 1:

Factory rest the door operator.
Please see the FAQ "How to do factory reset"

Step 2:

Uninstall the arm.

Step 3:

Follow the FAQ "How to install the door operator" make the spindle fully open, reinstall your arm and initialize again.