Switching between windows on Microsoft Outlook 365

Please help as this is frustrating me.

I run a mid-2012 MacBook Pro using MacOs Catalina 10.15.7.

The keyboard layout is British-PC.

I have the latest Microsoft Office suite.

On my Windows PC, I could switch between the two latest open panes using Alt + Tab. This works between applications or within one application.

For example, I look to edit emails in a full window and flick back to the main Outlook application to copy and paste stuff, re-read a different email and then flick back into the email I am editing. Super easy.

I cannot find the keyboard shortcut to do this using MacOS. I have read that the answer is Command + `, however this does not work for me - it just changes whether or not the reading pane is displayed.

Is there a shortcut? Or is there a piece of software that I can run which will help?

This is making my workflow so slow as I need to use the mousepad to put the cursor on 'window' and then select the pane I need. Slow!

Many thanks in advance.