I think it's trying to open your browser for google sign in, and facebook app for facebook sign in - sounds like there's something not functioning properly with opening other apps on your device. I have no idea what might be wrong with it - first time I've heard of the problem.
Simplest solution is probably to log in to the browser version on a desktop and convert to a spacetime account instead (nexus -> my account -> modify account), so it doesn't need any external apps.
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