Sure, I think you can achieve this using 2.38.2. I’ll try to help but I don’t know very much about how ACF saves its data.
MapPress works off ‘standard’ WordPress custom fields – the ones you see if the post edit screens by default.
I think ACF actually does save its data to normal custom fields but I’m not sure. I’d suggest setting up MapPress first without ACF, then adjusting it to use ACF fields.
To generate the maps: there are settings in the MapPress ‘settings’ screen that allow you to just specify the custom fields that contain an address or lat/lng for each post.
Once you set them up MapPress will generate a map for each post when you publish it. The process is described in the documentation but let me know if you’ve already read that and have questions.
I don’t know how to read the ACF fields for the template – that’s really more of a question for the ACF author – but my guess would get you could just use the regular get_post_meta() function in WordPress? Does that not work for ACF?
To modify the template, you copy it to your theme directory and modify it (file ‘map_poi.php’. If you need a sample template with a get_post_meta() call in it let me know.
I hope that helps…