Saving to Vault from different App's API

I'm using Alibre design's API to create Alibre Drawings through code and need to be able to save to the M-Files vault. I've asked a question about it on their forum but want to make sure that this isn't anything related to M-Files permissions. In their documentation for the SaveNew method it states:

"To save to MFiles vaults using the API, you will use the same methods as with the file system. The filepath should be passed with the following format: [MFiles drive letter]:\[Vault name] (ie. "M:\MyVault")" 


The function definition is this:

void SaveNew(
    ref Object pDestination
)

Parameters

pDestination
Type: System. Object
An IADFolder or windows folder path string.

I am not able to use a string for the parameter so I set the file path string equal to a blank object. While debugging I can see that the object is just the string:

I used DirectoryInfo to make sure the directory exists and it does.

I get this error when trying to save:

I'm not sure if this has to do with any permissions when saving new documents to M-Files through code and outside API's but I am consistently accessing M-Files in other ways in my program so I know my connection is established and working correctly. If anyone has any suggestions, I would very much appreciate it.