There's a couple of VM's on the volume, and they work fine, so the credentials would appear to be ok.
The problem seems to possibly be the archivelogmode of the oracle database, and the nimble user account not being able to do what it needs to.
Unfortunately I don't have login details of a user account with sufficient permission on the Oracle db to change the mode. So I may have to create a separate volume on the nimble with a protection group that doesn't try to quiesce, and put the VM on there.
Permission at the Application level does sound likely.
There has always been some discussion about using vCenter to quiesce VM's and my answer is "generally" to only to use Nimble vCenter integration for Microsoft SQL and/or Exchange VM's, both of which need VSS integration for a consistent recovery point and which VMWare Tools can perform via a software VSS quiesce prior to Nimble taking the snapshot.
Everything else is generally (I'll avoid saying always here!) recoverable via a crash consistent snapshot, including Oracle. See Oracle Support Note: Supported Backup, Restore and Recovery Operations using Third Party Snapshot Technologies [ID 604683.1] - assumes you can access this within Oracle's support system. (I have a copy if needed) - but ultimately Oracle supprts recovering form a crash consistent snapshot.
There is also a script in Nimble Connect to snapshot Oracle which may be of help: Create Nimble snapshot for Oracle DB