You should be able to download from there and just install, after removing your 5.4 version.
HOWEVER... it is possible the catalog changed format. Adobe provides for update compatibility and conversion but not downward, so it is also possible that it won't work at all, or may partially work and fail down the line. Downgrading is not always a good idea.
I'm curious - why do you care? Just don't use the new features?
LR 5.4 is a full Mac and PC version. There is an additional product LR 5.4 Mobile for an iPad. LR 5.4 is not an iPad application.
Gary in SE Michigan, USA. Nikonians membership - My most important photographic investment, after the camera. D4, D810, D300 (720nm IR conversion), D90, F6, FM3a (black), FM2n (chrome) YashicaMat 124, Graflex Speed Graphic 4x5 My Nikonians Gallery & Our Chapter Gallery
Yes, though that first letter is an L as in Lightroom.
So if you open the catalog, is everything OK?
>What kind of aircraft is that in you user name? I spent 15 >years in flight operations at Flying Tigers and FedEx.
It's a T-6 trainer, my wife bought me a ride in one for Christmas. I use to fly, but had been planeless for several years when she bought the ride. Fortunately it didn't resurrect the addiction, otherwise I'd have had to sell the cameras.
A group of about a dozen T-6s is based at Van Nuys Airport. That is in the San Fernando Valley section of Los Angeles,
From the Spring season on when air shows happen all around Southern California, these planes fly in formation over the shows. They are known as The Ghost Squadron. They come over my house 6 or 8 times a year because I am on their flight path if they go south.