Problem with data roaming package.

I’ve purchased a 15 day roaming whilst visiting Australia from UK. Whilst I’m out & about, I can’t access apps, which is kind of why I wanted data roaming ( for bus timetables, directions etc). I’ve done everything that Chat GPT instructed but no luck. What am I doing wrong

Is roaming enabled on the phone?
Are you getting signal
As most phones have data roaming disabled on device