Using an Xcode that supports iOS13.x b means you're obligated to support it. Making an app that doesn't complain when other OSs are in the mix is on the dev....you, but yes, within reason. 'within' in this context is the deep end of the pool, especially when you're new.
My advice is that unless you specifically want an app that attempts to support a beta iOS is to stick with release tools until you become more familiar. The beta tools are meant to allow devs to sneak peek their apps against an upcoming public OS release. You risk making things harder on yourself if this is your first rodeo, otherwise.
If you insist on pressing ahead, you'll need to show the calls and errors if you want detailed help - something more specific than 'not working'. Be sure to bias what you're seeing against the beta's release notes so you don't waste time tail chasing, etc.