Support Forum

first, simple press doesnt send the emails, WordPress does... we of course tell them what to send... but wp has issues with numerous hosts sending emails, particularly on shared hosting... the wp support forum is filled with topics on it...  usually, its server sending the emails, it can be fixed with a simple SMTP plugin (like HGK SMTP) for WP...  but lets dig further...

are you ad admin getting other emails from the forum (ie new users registering)?   have you done any configuring of emails options on forum - options - email settings?

also, keep in mind, that when you post to a subscribed topic, you wont get a notification since you already know about it as the poster...  best way to test is to subscribe with one user account and then test new post with other test user account...

I am not sure what you mean by enabled emails for admins and digests for users...  are you forcing digests?  If so, it will apply to all users regardless of admin, mod, user or whatever...  if you are not forcing digests, but have enabled them, then its up to users in their profiles to select individual emails or digests...  Or, are  you talking about admin notifications (forum - admins - your admin options) regarding admin emails?  If so, those are not at all related to the subscriptions plugin but simply a core function to send an admin an email on all new posts in the forum (except theirs of course)...  but its not a subscription... and only admins and mods can get those...  if you are also subscribed to a forum/topic, you will get two emails... one from the admin notification (if enabled) and one from the subscription..

if its just digest emails not coming, do you know if wp cron does not work on your site (its another common wp problem on some servers)...  the digest sending uses wp cron to send them...  you can test your wp cron, but creating  new blog post but instead of publishing it, schedule it to post automatically in 5 or 10 minutes... and then see if the post shows up as scheduled...

sorry, nothing attached...  please upload as attachment to the post...

who cares if it has not been updated in two years??  thats totally irrelevant for what it does...  very simple interaction with wp and no need for it to be updated...

the auto subscribe option (as the help says) only applies to new users... any existing user would not have that option turned on...  why?  because we cannot universally go apply it to all users when you enable it...  some users may have already opted out of it...

if you want to forcibly apply it to existing users, please check out the membership subscribe plugin... it has a way around that (even if we dont like how it universally treats users) where you can auto subscribe existing users when adding them to a usergroup...  so you would in essence move them from their current usergroup, then move them back in and they could get auto subscribed...  there are a couple of forum topics on the mechanics of that too...