This is a foolish requirement.

The casino team are trying to just stress you, why can't they ask for your wallet address and put that in blockain scans and look into your past histories themselves? Some online casino requirements are crazy at times, if this is bank account requires it is different, but asking for your income statement that is publicly available on the blcokchain sound stupid.

Anyways, you don't have a choice than to give them what they want, use blockchair or any other and download the PDF, I am not sure that Electrum wallet has that feature.