Does anybody know if it's possible to map a string field to a date field?

We have our Zendesk user profile provisioning coming from Okta. I've mapped a bunch of the Okta profile fields to custom user fields in Zendesk (title, department, manager, etc.), and that's all working great. I would like to have our Hire Date field mapped to a user filed in Zendesk as well

The issue is the Okta "Hire date" field is a string field, and I'd like it to map to a Date field in Zendesk. I want it to be a Date field because I could use this for all sorts of awesome reporting in Explore. I mapped the field to see if ZD was smart enough to transcribe it into a date selection, but I'm getting a NULL value. 

Does anybody have experience accomplishing something similar? Does the date in the string field just need to be in a specific format for it to work? Do I need to use a in-between integration tool like Workato to format the value for me?

Thanks!