How to download multiple files from Google Drive.

If they're all showing in the window:

1) Do a shift-leftclick on the first and  last  one  that  you  want.
Their names should change colors to indicate they've been selected.

2) Right-click on the 3-vertical-dots icon (top right). This will get
a  popup  saying  it's making a zip file (which seeems to be the only
way to do a download).  This might take a while.

3) When a Finder-style window pops up, with  "Save  As:"  next  to  a
file-name  widget,  type  in the name you want for the zip file.  You
shoulalso be able to select a directory using the rest of  the  popup
window.  Click on the Save button when you're ready.  the window will
disappear, and the transfer should be done.

Sometimes the zip file won't be where you thought you said to put it,
and you have to hunt for it.