how can i find the time of an app installation

All, I have received a parking fine, £100 and I need to provide evidence of what time I downloaded the app. I was on the app for 7 minutes. I cannot find the time I downloaded the app. My screentime says 7 minutes between 9 and 10 a.m. so is not specific. I know if I downloaded the app I would have continued to set up and pay. The bank did not pass the transaction until 11:15 that day, and I need to prove that I have did do everything within the time.

Can anyone help?