RE: Exchange Online subscription
Hello,
What are the other licenses in your Office 365 organization?
If you already have users on Business (Premium), or Enterprise (1, 3, or 5), then 'Exchange Online Plan 1' or 'Exchange Online Plan 2' would be the best choice. The Kiosk license shouldn't be combined with Business or Enterprise.
Exchange Online Plan 1 and 2 don't come with a License for Outlook on the desktop but, if you already have a copy, you can connect it anyway. So if you're a different user, with a License for Outlook on the desktop and want to add this extra generic mailbox to your Outlook, that's totally fine.
Here's a quick overview of the differences:
https://techjourney.net/office-365-exchange-online-plans-1-2-kiosk-differences-and-comparison/
I've never tested Dynamics 365 with a Kiosk license but, that's primarily because most Dynamics customers will have Office 365 Business (Premium) or Office 365 Enterprise anyway, and then you're not allowed to use the Kiosk license.