What step by step process should be taken for testing a new cross platform mobile app that is build for the first time?

What step by step process should be taken for testing a new cross platform mobile app that is build for the first time. The app shows geolocation info. All the tasks are organized in Agile with 2 week sprints. The testing should be done only for the mobile app (not for API or other services) , and it should be done for Pull Requests and before a production release. Which tools should be used in this process? What manual and automated steps should be followed for testing , and the people involved in manual steps ? Also, how should the issue reporting be done?