There might be a relation, phasic vs tonic dopamine. But given the anecdotal nature of the ADHD-creativeness link, I’m not so sure. Would need to see some papers about if first.
Anyway, ADHD is comorbid with plenty of other disorders that are limiting on creativity such as anxiety, low self esteem, inhibited decision making, that it’s definitely not a given.
Anyway, it seems much more likely that there would be a causative link between ADHD and creativity- e.g. some common underlying factor that boosts the explore tendency in explore/exploit along with openness to experience. A brain that naturally roams more could be expected to produce more novel syntheses.