@Anonymous ,
I assume the number is the field you created, so you will need "Ask in PowerApps" and pass the value in the Flow - this will be an additional parameter for you to include - you will have to disconnect and reconnect the Flow for PowerApps to pick it up.
You can add the Parameter once in PowerApps and use it for both - the first (as above) is Ask in Power Apps - you can then look in your existing list of these and include it again in the second file parameters (it will the the same "icon" title in the list at right).
The ItemID refers to the one in your Create File action - you will have to find the right one in the list at the right and include it - that is how the Flow knows which file to include the parameters on.
You can leave Title blank unless you want to put something in there as well.
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