OAuth and import/sync-integration

Im building my own trading journal site and I want it to have the function to directly copy my trades into the site using import/sync-integration like for example TradeZella. I was wondering what the rules are regarding this and if its allowed for personal use. Another question I have is, what is allowed if it so happens that I launch the website and sell it with subscriptions or is that something I have to ask the propfirms?