I have my app built and shared with a co-worker. Because the App is linked to my BOX sync account, it is asking him for my BOX Sync login to open the app. I have added him to the folder in BOX also, so he should be added in both places.
Could you please share a bit more about the app that you mentioned? Is it an PowerApps app?
Do you share your PowerApps app with your co-worker?
Further, do you have shared the connections with your co-worker?
If you share an app with a co-worker, when your co-worker run your PowerApps app first time, a dialog would be shown up to ask providing credentials to run this app as below:
You could consider take a try to share the app resource with your co-worker and let your co-worker to run your PowerApps with your credentials. More details about sharing app resource in PowerApps app, please check the following article: