Steve,

As far as I can see its not Luhn 10 checksum but rather processing the numbers at the bottom of a printed cheque/check - https://en.wikipedia.org/wiki/Magnetic_ink_character_recognition

the regex...

I would say your only option is to use a CLR to do it. 
https://www.google.ie/search?q=clr+regex+c%23&oq=regex+clr&aqs=chrome.2.69i57j0l5.5556j0j7&sourceid=chrome&ie=UTF-8 will give you some examples

or eventually R https://www.mssqltips.com/sqlservertip/4748/sql-server-2016-regular-expressions-with-the-r-language/

That is not a local drive then - it is a cluster resource which is not what this thread is all about

Being on the NAS may be the problem - drive should be local, not networked.
This probably should be added as a disk through VM for it to work outside...

Tom what is the SQL version you are using?

I am sorry but not much you can do without them fixing the extraction of the data.

Lets analyze the sample you gave us - which I trully...

Is that really the content of the file? if so it is a piece of crap data really.

ADV ,A_DAT ,A_TIM ,P_tit ,S_Tit
"SOCLEAN INC","5/16/2018","14:39:44",""Z-QUNICY,"DR K 60...

Take in consideration what Steve and Sue said and look at better/correct ways of doing your process.

However just as a possible rewrite of what you have you can...

on the counts replace the "else 0" with "else null"
e.g change
COUNT(distinct (CASE WHEN obranome LIKE 'C%' AND etotaldeb <> 0 THEN obrano ELSE 0 END)
to
COUNT(distinct (CASE...

If referring to PowerBI Report Server then any will do - but be careful with licensing - either you have a Enterprise edition with SA (and you can then install...

instead of presenting 8 vcpu with 1 core each present less vcpu with more cores. that will sort the licensing limit

you may be able to - but being a DMZ you probably should not anyway.

have a look at https://www.experts-exchange.com/questions/25053526/Passing-user-credentials-from-a-trusted-domain-through-SPN-and-Delegation.html. this contains other links that may help you...

did you install SSDT also?

https://docs.microsoft.com/en-us/sql/ssdt/download-sql-server-data-tools-ssdt