Adding Rows to Excel file with PowerApps

We need an application based on PowerApps from Office 365 which will add new rows at existing Excel file in SharedPoint. Each user should authenticate (login/password) at the beginning of the application (not Office365 user). The username/login/pass values are in another Excel file, for example "[login to view URL]" (or other file on same SharePoint) The steps are: - Authentication (Login, if user is not yet authenticated) - Choose date/time (Default value is NOW) - Choose a Source (Select or search values. The values are collected from a "[login to view URL]" or another file. The source values can be combined with “+”) - Fill values - Submit data - If OK - confirm to user that the data of (%SOURCE%) are saved successfully, If KO - retry Submit Action - Go to Authentication Screen Requirements. Each step should be on different screen, but Username and Source are showing always. Until "Submit" action, the data must be saved in the application (local) and permit the user navigates between application screen (prev/next) and edit the values. Each “Submit” action should add next row in Excel file and clear all fields in the application. For the integer (or real) values fields, it’s showing numeric keyboard only. The username and password of our Office 365 will be sent you for development environment.