How we can access SharePoint 2019 on-premises on mobile device Android + IPhone?

We tried to access SharePoint 2019 on-Premise in our android device after installed the SharePoint Apps in google play store.

We tried to login through SharePoint server url option. but not get the success. we got the massage “unable to connect to SharePoint server please check the URL, or make sure your deceive is connected to your corporate network” Please give the advice how we access SharePoint using mobile apps.

Is we need any extra configuration?