When you deploy Cloud Proxy, you need to configure Cloud Proxy's Collector Group as VMC's vCenter adapter's Collector Group.
In this case, NSX-T adapter also refers to VMC's vCenter adapter's Collector Group as their own Collector Group by default.
However, the above credential error will be reported because you cannot login NSX-T with Cloud Proxy's Collector Group.
You have to change NSX-T adapter's Collector Group to Default collector group individually as followings.
- Go to VMware vRealize Operations Cloud > Administration > Solutions > Cloud Accounts > Choose your VMC adapter.
- Open pull down > Choose NSX-T adapter > click 3 dots > Edit.
- Configure Default collector group as its Collector/Group individually.