The code you are using becomes eschewed because you put align tahs aroud the images before putting gallery tags around them.
In the example above you have
Code:
[align=center][gallery][/align]
[align=center][img]https://i.imgfly.me/jH1kIF.jpg[/img][/align]
[align=center][img]https://i.imgfly.me/jH1Wsv.jpg[/img][/align]
[align=center][img]https://i.imgfly.me/jH1FSA.jpg[/img][/align]
[align=center][img]https://i.imgfly.me/jH1Zeb.jpg[/img][/align]
[align=center][/gallery][/align]
which won't work, where as the code below will work
Code:
[align=center][gallery]
[img]https://i.imgfly.me/jH1kIF.jpg[/img]
[img]https://i.imgfly.me/jH1Wsv.jpg[/img]
[img]https://i.imgfly.me/jH1FSA.jpg[/img]
[img]https://i.imgfly.me/jH1Zeb.jpg[/img]
[/gallery][/align]
Also note that on any one page, only 1 gallery will work so you cannot have multiple galleries.