Packages, or Applications, on Linux can be installed a number of ways. This demonstrates the true freedom and power of the Linux Operating System, and while it may be confusing to newcomers, you’ll quickly learn that you can get software just as easy as you can on Windows or macOS. However instead of only one software center, you can enjoy many others to get the packages or applications that you need.
Package Maintainers on your Distribution
.deb packages / APT repository
AppImages
Flatpaks
.zip or tar.gz compressed files
Snap Store
building from source code (advanced)
For Flatpak improvement, try these easy tweaks: https://itsfoss.com/flatpak-tips-tweaks/