Themes for Keynote app is available in Mac App Store. Click here to download Themes for Keynote app from Mac App Store. Download will start automatically by tapping install app in Mac App Store. Once downloaded the app will be located in your Mac's Applications folder. Check for "Themes for Keynote” app in the Applications folder, through the Launchpad or in the Spotlight.
Can I have this app on my second computer?
Yes. You can use the app on up to 5 Macs using the same Apple ID. Just run the App Store app with the same Apple ID on the second Mac and go to the Purchases tab. You'll see a list of the apps you've already purchased, with an Install button next to each one - click the button to install on the second Mac.
I have changed computer and In-App purchases aren't showing up as a purchased anymore. How to restore purchases?
You can re-download any in-app purchase for free using the same Apple ID. Sign in with the Apple ID, open the app window and wait until all the prices will be loaded on the buttons. Click the app name and select "Restore Purchases" from the top menu. The download process will begin for all the in-app purchases you have purchased earlier. Of course they will be downloaded for free. You can see that in the picture below:
My in-app purchase download was interrupted. How to resume downloading?
Most of the Keynote Themes contains movies (Moving Backgrounds) inside and the files are quite large in size(one category 300-600 MB, all categories 2500 MB) due to high definition quality. It can take some time (even several hours) depending on your internet speed to download all categories. If the downloading process was interrupted because of the internet connection problems, the download starts from the beginning after the app is re-opened.
The apps with the In-App purchases work different and require more patience to download and work with them. It is just different type apps. They are strongly related with the internet connection and server system. Wait until the download will be finished without interruptions and you will be able to create awesome presentations with the Keynote.
You can try to download the themes during the night or in some time when your internet provider’s traffic is lower you can use wi-fi or some faster internet connection at your work or friend’s house.