If you want to have reflow, then there isn't a whole lot you can do but wait. The Basic has few buttons and no touchscreen, so I don't think you can copy over a version of AdobeViewer.app from one of the other PocketBook readers and have that work well.
The
k2pdfopt program allows you to reformat PDF files to new page sizes. You could download that for your PC, convert your PDF files to fit the screen of your Basic ereader, and read those instead. That way, you wouldn't need reflow to work on the device. See the thread here:
https://www.mobileread.com/forums/sho...d.php?t=144711