To use the in-build selfie function you will need to give Socios.com permission to use your camera.
You can do this by following these steps.
Tap on the Profile section in the top left corner.
Tap on the 'Personal verification' tab.
Fill in your personal details.
Choose your identity document and fill in your details.
Select the 'Use camera' option.
When prompted tap 'Open Settings' and give the Socios.com app permission to use your camera.