Hi Mark,
You can indeed use ACF with events, similar to how they would be used with other post types (events are the “tribe_events” post type – see screenshot).
Is there something specific that you are trying to do with the custom fields? We are limited in the amount of support that we can provide for customizations and integrations, but if you get stuck on something, please let me know! I’ll be happy to see what I can recommend.
I would also point out the additional fields feature that comes with Events Calendar Pro. These are custom fields that you can add to events, the values of which will be included on the front end of the event by default.