It is possible that your download manager doesn't support the files in Drive.There's no need to worry, the solution is to create a direct link of the files, which can be clicked on from anywhere.
Step 1: You can share a folder with the public.
Right click on folder, click share, and then from the appeared window, in the part "who has access", select "Public on the web".Click "Save" after that.
Step 2: You should put your files in this folder.
Move them to that folder if you have already done so.
Step 3: You can open your public folder.
Click on your file and select "Detail and Activity".The right side of the screen will have a pane added to it.
Step 4: The "Details" tab is in the details and activity section.
Step 5: Until you see "Hosting", scroll down.
You have a direct link to your file.You can put this link in your website.The link can be added directly to download managers or you can resume it later.