Enabling that extension won't help you here. At least, not without a bunch of extra work.
The PDO ODBC driver cannot be used to connect to databases directly. Instead, it's a sort of "wrapper" for other ODBC drivers. (For instance, if you had an ODBC driver for MySQL, you could use that with PDO ODBC to connect to a MySQL server. Which would be silly, but whatever.)
Anyways, as far as I know, there is no free ODBC driver available to connect to Access databases. There is a commercial one out there, but it's rather expensive; unless you have a really pressing business need, you're probably better off putting your time towards converting this database to use MySQL or SQLite.