With the freeware LISP utility DWGpropsCSV you can set the values of the drawing properties (DWGprops) of all DWG files in the whole folder at once, according to an Excel table with the property prescriptions.
Download the DWGpropsCSV utility from Download, load it into your AutoCAD using APPLOAD and run it, even in an empty drawing, by typing DWGPROPSCSV.
In the first prompt, enter the name of the text CSV (comma/semicolon-separated values, e.g. from Excel) file containing the prescription (import-rules) for the property settings. It may look something like this:

Lines beginning with a semicolon are comments. The first content row contains a list of property names to be set (column names with property values). One of these properties must be DWGNAME - the name or wildcard mask of the DWG filename.
The next lines of the file then list the property values for the individual DWG files. The individual files are identified by their filename in the DWGNAME column, or collectively by a mask (wildcard), perhaps even just "*" for uniform property settings applied for all DWG files in a folder. If no name in the table matches the name of the currently processed DWG file, no changes will be made to it.
You can set both standard properties, e.g. "Author", and also set/add any additional custom properties.
In the next prompt (dialog) you specify the folder from which all DWG drawings will be successively processed. However, the actual property settings (changes) will only be applied for DWG files whose name is specified in the CSV file (DWGNAME column) or whose names match the specified filename mask. The property settings will be applied from the first row of the table that matches the DWG name.


Note: If you want to use comma-separated (or semicolon separated) CSV files even in local environments, set the LISP variable:
(setq _CSVdelimiter ",")