Calendaring/Mail has always been a weak point, there’s not a ton of development happening in this space. I use Office 365 for work and I’ve tried everything, Evolution works via EWS, but even when it’s working perfectly the UX hasn’t caught up with the modern web clients. I’ve tried 2(!) paid extensions for Thunderbird each with their own various problems.
I’ve had ok success with minetime plus Mailspring. Bluemail works well but doesn’t have a robust calendar.
None of them are stable enough to set up a meeting with without embarrassing yourself at work, so I settled on Prospect Mail, which wraps the Office 365 webapps in an icon/window on your desktop and integrates the notifications.