gmail does not show messages in outlook -- install as imap?

I have a OnePLus 7 (not Pro) and use the Outlook app for certain reasons (work). Because I don't want multiple mail programs if I can avoid it, I always had my Gmail account in there which always worked fine. But now, not sure if this is an update, my Gmail account has become unresponsive. If I delete the account and then: 1. add it via "Add mail account" -> add Google account, it asks for some permissions the Google way and does not complain, but it does no show any emails, not even the unread ones. I'm "done for the day". 2. add it via IMAP (selecting *not* Google) after setting "IMAP enabled" in my Gmail account on the browser, using these directions , it says: Log-in error Please check your email and password and try again. For route 2 I'm sure the problem is not the e-mail or password, because those work in the browser. And route 1 does not seem to work as it does not load messages. Does anyone know how to access Gmail as IMAP on and Android device? Does it require the 2-step verification somewhere?