Some of the new third-party iPad apps to arrive on the Mac via Catalyst included Rosetta Stone, GoodNotes, Carrot Weather and Twitter. More than 30 are now curated in a section of the the Mac App. If you are successful in getting apps on this iPad, consider looking for more “up to date”, third party iOS web browsers for that version of iOS. I would STOP using that nearly 3-year old Safari web browser, as it is, probably, not safe and secure to use any longer, and seek out a third party web browser that is STILL currently being.
In order to protect you from malicious apps on your computer in Mac OS X Lion, Mountain Lion, Mavericks, and Yosemite, Apple has built in a setting you need to know about. The setting, called Gatekeeper, allows apps installed directly from the Mac App Store, but it prevents installation of apps from anywhere else. I wanted to download RStudio and was able to download, but not open because of Gatekeeper. I was positive I trusted the developer, even though Apple does not, so I decided to change my settings to allow it. This is how I did it and how you can do it too from any app developer that you trust.
In this case, I want to open an app that I download from the internet, RStudio, but because Apple does not trust this developer, I need to change my settings. First thing I do is determine this is an app developer I trust. Then, I open settings and click the 'Security and Privacy' icon.
After you click on the General button to the top left of the security window, you will see a portion that is locked called, 'allow apps downloaded from.' You want to unlock this portion so you will need to click on the lock icon on the bottom left corner of the privacy and security window. You will be prompted to enter your password.
Click the option 'Anywhere,' that removes Gatekeeper's blocking capabilities on your Mac, allowing you to download and open any app of the internet from an app developer you trust. I recommend only downloading from sources you trust so you don't wind up with an app downloaded with malware backed in.
After changing my settings, I was able to open and run RStudio with no problem.
Third-party apps and extensions expand your editing options in Photos for iOS and macOS. You can apply edits from multiple apps and extensions to one photo, or use any combination of apps and extensions plus the editing tools built into Photos.
Learn how to find apps with Photos extensions for your iOS device, turn on the extensions, and then use them to edit photos.
Use the App Store on your device to find and install apps that allow full editing from Photos or include extensions for Photos. Apps that include Photos extensions often say so in their descriptions; search for terms like 'Photos extension' to explore more apps.
You can also choose from the apps listed in Edit Images Faster With Photo Extensions on the App Store.
After you install apps that include Photos extensions on your iPhone, iPad, or iPod touch, turn the extensions on:
Learn how to find apps with Photos extensions for your Mac, turn on the extensions, and then use them to edit photos.
Photos for macOS makes finding third-party apps easy:
The Mac App Store opens to a selection of third-party photo editing apps that are compatible with Photos.
You can also choose from the apps listed in Extensions for Fast Photo Edits on the App Store.
After you install apps that include Photos extensions on your Mac, turn the extensions on:
With Photos for macOS High Sierra and later, you can send a photo to most third-party photo apps for editing, then save the changes right back into your library.
Your edited photo appears automatically in Photos.