I think my download and install actually didn't create the files that the game would save data into. Look under Documents/BioWare/... and see if there is a file for "Mass Effect Andromeda" there. If not, you'll need to make one. Then, go back to the BioWare (and possibly the "Mass Effect Andromeda" ) file and right click on it. Click on "Properties", and then click on "Security". Look at the names in the window that says "Group or User Names", click on each of those and see what "Permissions" they have. If the one with your name or the Admin access are missing some checks (like read and write), hit the "Edit..." button and give that User/Admin access (The "Special Permissions" box will almost never check, so I didn't worry about it.).
Even if the "Read Only" box comes back ticked, my game saves and other data are all still being kept, so it feels safe to say that that particular thing can be ignored, if all the rest starts to work for you like mine did.