You can get all the information from the exchange official social media handle or help center. I'm very positive most of the well known exchanges have mobile app used for trading cryptocurrency.
Did some search and found this article online, you can read through it and make a decided on the exchange App you'll love to use.

Article: Best Smartphone Apps For Trading Cryptocurrencies On The Move

Also you can trade with binance mobile app, contact the support center of binance to verify if you have downloaded the official mobile App it could be a clone.