You’ll need to go into the 3.6 driver details on the Dell support page. Or use the arrow on the far right to show more download details. There’s an ‘Older Version’ link you can click on to see all previous versions you can grab. Here’s a link to 3.6 details:
You’ll need to get to at least version 3.3 before you can upgrade to 3.6. Check patch notes for specifics.