Android won't auto fill an app under Android because the domain in the password entry doesn't match what the app is using. How do I find what the app is using so I can enter an equivalent domain for it?
You can configure app/URL associations in your autofill settings.
https://support.lastpass.com/s/document-item?bundleId=lastpass&topicId=LastPass/t_lastpass_android_manage_settings.html&_LANG=enus