Dynamics CRM 2015 Sync config : step 3 - Select Fields to Sync is spinning
Hi,
I am new to Marketo and trying to integrate dynamics crm 2015 (onprem). I have imported solution to our ORG and set a admin user with marketouser role. I am on step 3 where I click and open "Select Fields to sync" and it is keep spinning and not loading (As below).

I tried in both IE / Chrome and same error. In fiddler, I see error 500 but in UI it just spins. Please help.

Note: When I do validate sync step. I get below error -though I have confirmed the user in marketo is configured in default CRM config as well with Marketo sync User role.

Appreciate your help.