I can relate to this. Not long ago I found the solution. 5G is definitly enough space. Try turning off your device and then turning it on. It sounds stupid but I swear it works! After you turn it on just install the app. Try not doing anything while it installs. It can take a bit - for me it was like 5-10 minutes. It works for everyting that involves installing.
Saving space tip:
After you download the file you can move it to a flashdrive, SD card or something like that. When you do that you get a bunch more space so your device can relax!