I tried doing every step from the verbose log, and the only place it really breaks is on the New-OfflineAddressBook command since one of the parameters are System.String[] instead of <Exchange FQDN>OAB (Default Web Site)

If I change it to the correct the command executes properly.

hmm,

Well i assume something is missing or different as to why it won't be able to get the variable.

Just to try things: can you execute the IIS Powershell installation script included in the manual:  https://solidcp.com/kb/installation/install-solidcp-standalone-server-within-5-minutes/

this way we know for sure your IIS has all features installed it needs for solidcp.

Can you also tell me the windows version, aswell as asp.net version installed? (4.5 / 4.6/ etc)

I tried running the powershell from the above page and it came back with no changes needed on the enterprise server.

Should I run the same script on the Exchange server?

Both servers are running Server 2012 R2.

I have installed .net 4.5 - all sites in IIS are set to 4.0 though.

I seem to remember having some difficulties setting Exchange up the first time - something with the powershell commands not being able to be run because it couldn't load them unless I put them in my powershell profile..

Isn't there a log on the enterprise server like the one on the Exchange server for all SolidCP stuff? I can't seem to find it anywhere.

Yes on your Exchange server too.

In the end it's not passing the query which most likely errors out due to a missing resource (it's an expectation as to the reason why the script returns a system.string[] instead of actual values).

Exchange 2013 should be fine to run without customization on asp.net 4.5

Only exchange 2010 has issues with asp.net 4.5 as far as i know.