You can use Remesh to retopologize your draft models. To do this, select a draft model in your generation history on left sidebar, then click Remesh on the right sidebar, and adjust your configurations by switching Topology to Quad, and confirm. After the Remesh process is done, you can then select the remeshed model for downloading. For more detailed steps:

First, select the model in your workspace that you want to have Quad topology for, then click on Remesh on the left side panel:

From there, click on Quad under Topology. Then, hit Confirm. It'll then remesh the model:

Then, you'll see Quad under topology. Then, hit Download the bottom of the screen.

Please note: Meshy automatically triangulates uploaded models.