Welcome in the forum 
In /e/, there is an Apps Installer. But all apps aren’t in there si Aurora Store (tuto here) is a good option if you don’t finc what you want in the /e/ Apps installer.
You have to carefully check if your phone model is compatible with /e/. All S5 aren’t the same for instance.
Go into the list of officially supported devices : https://doc.e.foundation/devices
Click on the phone you are interested in and scroll down to “Supported Models”. Check if yours is in the list.