An annoying feature of Gmail (GSuite) is that after a while it will stop you from logging into your email via Outlook (or other client app), and when you go to turn on access via Less Secure Apps, it will tell you that:
This setting is managed by your Domain Administrator.
For me, was working fine with Less Secure Apps turn off, then it stopped working after a few days (just when the free support ran out). Then it actually allowed me to turn on access from Less Secure Apps, but still didn’t work. A few days later, I then went back to the same setting, which was greyed out and I couldn’t enable access from Less Secure Apps. I was logging on as the Domain Administrator the whole time, but was told that I couldn’t change the setting because it’s managed by my Domain Administrator. Genius! 🙁
I fixed this, by logging onto the Admin Console (as the same Domain Administrator account as before!), then navigating to the setting to enable Less Secure Apps for everyone. After about 2 minutes, I was then able to use my Outlook client.