I think Quinn as-is, meaning minimal improvement over the next year, is probably a 4th-5th rounder. He has the arm and some other nice traits, but he's too far away from being an NFL starter to spare more than a mid round pick. If everything pans out, he might be a backup 2-3 years down the road, and might be a starter by his second contract.
If he takes a natural small step forward due to another year in the system and the college game slowing down, he's probably a second rounder similar to Drew Lock. That's a year one backup with sub replacement level starter upside in year two, and possible average starting level play at the end of his rookie deal.
If he takes a big step forward meaning he improves at his weaknesses (inaccuracy down the field, issues reading defenses especially in the middle of the field, not being constantly injured, not feeling premature pressure) and his more consistent week to week, he'll be a first rounder. That's a day one starter with above average starting QB upside.