@aut Follows are part of ActivityPub. The other party gets a notification, depending on their settings he may have to approve your request, and if he blocks you it will remove you as a follower. If you follow someone, you get to see all his posts at the "follower only" privacy setting, and he may reciprocate by following you back.

Subscribes are essentially a way of scraping the other party's public feed. Neither he nor anyone else gets any notification, and the only way it is stopped is if we get blocked at the instance level. It tends to be more robust, because as long as the other instance allows QOTO to fetch its RSS feeds, it will work even if authentication or something breaks. But the tradeoff is you don't get to see "follower only" posts and he won't know to reciprocate.

Generally, if following isn't working at the technical level, it's worth trying a subscription. It's also a useful technique if you think following that person might expose you to harassment, because each person's follower lists are public. So if you think there might be a cyberbullying campaign targeting followers of a controversial account, it's safer to subscribe than to follow.