For a number to be divisible by $9$ in Base-3 representation last 2 bits should be $0$.
So, DFA will comprise of $3$ states and will look like $\Rightarrow$
$9 = (100)_3$, $18 = (200)_3$, $27 = (1000)_3$ and $36 = (1100)_3$ and Above DFA accepts all these strings.