The owl plugin for Thunderbird is very good. I have bought a paid subscription to that. Everything works fine with Thunderbird now.

I set up Evolution for my work office365 account. It worked exactly for 2 days. Now, it constantly keeps asking for password again and again and nothing shows up. I'm trying out Thunderbird with Owl plugin (trial) and that works flawlessly. Any tips on getting it to work on Evolution?

I understand your point completely. I'm a long time Arch Linux user, so I'm not averse to manual interventions.

I was considering tumbleweed on my work laptop. This makes me nervous. Was it easy to fix?

Do read up about the philosophy of puppy Linux. They are based on different distributions like Ubuntu, Debian, Slackware, etc. Puppy Linux aims to make these small and efficient with some minor utilities thrown in. So, for actual support, you can rely on those distributions as such. Any updates, software installation, etc can be had from the base distro itself.

Try Puppy Linux on it. It runs with meager resources - ~100MB RAM, 250MB storage (only if you want to install it to disk). Everything runs in RAM and is blazing fast. It is a God send for older computers