PROBLES SENDING EMAIL OR UPLOADING FILE FROM META QUEST 2/3

I don't know if this is the right place but I need help, I am making an application in unity with quest 2 and 3, the application has several scenes with different tests and accumulates results and saves them in a jpg/png image file and in a PDF.

This file must then be sent by email or uploaded to an FTP, or in some cases both.

When testing the application at run time from the PC through Airlink or cable the scripts and configurations work perfect, it sends the emails through a gmail service and uploads the files to my personal host through an FTP configuration.

But when I compile the app, nothing works, it does not send the emails and does not upload the files to the FTP, in both cases it says access denied. as if it could not read the files inside the data persitency folder or if the app could not have access to the outside through internet I would like to know how to solve this, since it is necessary that the app does what I need it to do. Thank you very much.

I'm going to make an somewhat educated guess that it is because there is no smtp or ftp service compiled into your app. It doesn't know what an email is or how to send one.. On the PC it would be running the ones you have on the PC. You could conceivably use a REST-based service to forward your email on or you could write such a service and host it yourself.

OK, I thought not really, because I have read that it was not necessary for android apps to have an internal server, only with external calls you could. Evidently NO, I never worked with REST, I'm not a backend developer, I'm more of a generalist coder.

Do you know where I can find information to set up a smtp server so that the app can send emails?

amazon SES would be something like REST or is it something else? if so these days I've been trying to set up the amazon SES service to send email but I haven't finished configuring it yet.

If you could guide me to investigate it would be very helpful.
Thanks for your time reading and answering.