So when there was a premium option, I think the limit was 10MB total for all attachments, for non-premium members. I don't think code repository, or PMs was included in that limit but I could be wrong. If you go to your "My Settings" then click on "Manage Attachments" you'll see the attachments I mean that were part of the limit. I was getting close to that limit when I became a moderator which had unlimited, and same for premium at the time.
I assume if there is no limit shown in the Manage Attachments page for normal members, then that means there is no limit. Or rather no practical limit, if you upload 2TB of VIs I'm sure Michael might do something about it.