Outlook Calendar share with 2 computers and mobile phone

I want to use the New outlook for Calendar only. I use Thunderbird with a pop account for email

What account would I use to share the calendars.

I am answering my own question.

If I choose Outlook.com email all 3 devices see the same calendar.

I could never get the Outlook to open with the calendar at startup. With 24H2 fresh installation, it does open to the calendar.

If you are using email on multiple devices you should really have Thunderbird configured for IMAP rather than POP. This way your email will be synchronized across all devices.

I use Thunderbird POP account on my Desktop and Laptop. I have not tried IMAP in decades on the internet. With Outlook on my Android phone, I did not have to choose any email. I presume it chooses Outlook.com by default.

This is very convenient. If I am at a doctor's or dentists office and am given a follow-up appointment, I will check the Outlook calendar on my phone to ensure that there are no conflicts with other appointments. As you get older doctor's appointments increase exponentially