Need help ASAP - SSAS Tabular error has me stumped and others' solutions do not apply in this case.

Question

Hello everyone,
Here's hoping no one will consider this to be the wrong forum. The data source is an Access database, but the issue is an SSAS Tabular issue. Kind of desperate here... the customer needs this ASAP, and I've been trying to resolve this for a week
already! Any help would be much appreciated!
A customer of mine (another employee of the ComIT department) is receiving an error trying to open an Access database via SQL Data Tools.
The error is "OLE DB or ODBC error: The Microsoft Access database engine cannot open or write to the file '\\[our_domain]\[the_path_to_the_file]\[database_name].accdb'. It is already opened exclusively by another user, or you need permission
to view and write its data.; 3051."
What perplexes me is that I do not receive this error, my coworkers on the DBA team do not receive this error, and our boss does not receive this error--even on the customer's machine. But the customer gets this error every single time.
The only difference is the credentials provided on the "Impersonation Information" window.
Here is our process:
We open SQL Data Tools, we create a new Analysis Services Tabular Project, we select the workspace server (our Analysis Services server... db5079\tabular) and test connection ("Test connection succeded") and click OK.
Then we click "Import From Data Source," select "Microsoft Access," enter the full network path to the database and test connection ("Test connection succeeded")
The next window says "Impersonation Information - Specify the credentials used by the Analysis Services server to connect to the data source when importing and processing data"
The credentials provided at this point is the only difference between me/my team/our boss and the customer. If we use our own credentials at this point--even on the customer's machine--we receive no error and everything is fine.
If we use the customer's credentials, we get the error above at the end of the next step (i.e., after we choose the data to import and then click Finish).
So that's it. On the same machine, the customer's credentials produce this error, and our credentials do not.
I have already added the customer as a server administrator to the Analysis Services server (db5079\tabular).
Copying the data source to another folder on the network or to his local machine produces the same results: his credentials produce the error, my credentials/my boss's credentials/etc. do not.
All of our machines are 64 bit, and the Analysis Services server is 2012 64-bit.
Please help!

Answer 1

UPDATE: As it turns out, all those who were able to import the data were local administrators on the Analysis Server (i.e., on the OS), and all those who were unable to import data were not.
When we added someone who couldn't import the data to the local Administrators group on the Analysis Server, they were able to import the data.
However, we can't give them local admin on the Analysis Server, and we are unable to determine what combination of user rights and permissions on folders we can grant the user as individual that will allow them to import the data.
Just as a test, we tried giving the user the same user rights that the admin group has, and the same permissions on all the drive as the admin group has, but that didn't work.
If it had worked, we could have started reducing the rights until we found the minimum necessary, but it didn't and once again we're stuck.
Please help!