Hi George,
Dynamics 365 for Marketing is licensed per tenant, if there is Marketing app included in the package, then all marketing functionalities will be available to you.
Total marketing emails you can send is based on how many Marketing contacts you have in your database, its total number is equal to ten times your marketing contacts quota
Definition of "marketing contacts":
Contacts who are engaged with marketing activities such as landing pages, forms, LinkedIn integration, events, and surveys. Contacts that you never engage in marketing activities won't be counted as part of this quota.
You can check whether Marketing app is available to your tenant in power platform admin center.
https://admin.powerplatform.microsoft.com/resources/applications
You check quotas of your marketing application in the app > Settings > Overview > Quota limits
In a word, please check whether Marketing app is included in the pack, and if yes, total marketing emails you can send is based on how many marketing contacts are included in that pack subscription.
My thought:
From my research, it seems that only Dynamics 365 Customer Engagement is include in Action Pack, so the Marketing may not be included, you could contact Sales to confirm the app availability.
https://dynamics.microsoft.com/en-us/contact-us/
You can set up a trial in the following link:
https://trials.dynamics.com/dynamics365/marketing