I downloaded the new DMG file, and then installed to Applications. No error messages (though it didn’t ask for an admin password). However, when I open LO and ask it to check for updates, it still reports that I am using 5.3.0.3. I’ve tried it twice, same result. LO is closed when doing the update. OSX 10.11.6
Figured it out. I unwittingly had 2 copies of LO on the machine (probably the result of a previous update error), and the update successfully replaced the one I was not using. Got rid of the other one and all worked OK.
Launchpad only showed one of the two copies, and to find the other one I had to go to the System Report.