Qualified maps wait in the ranking queue before they're ranked. On somtum.fun, each qualified map is ranked 1 day after it was qualified. There is no daily limit, so maps don't have to wait for each other.
You can see the queue in the beatmap listing. Each qualified map's page shows when it's expected to be ranked.
If a problem is found while a map is qualified, it can be disqualified. It goes back to pending, its nominations are cleared, and it needs to be nominated again. A map that was disqualified waits longer before it's ranked again (up to 7 extra days).
See the ranking procedure for the whole process.