Yeah, you have to install all the installers, it's really weird but I guess they just weren't able to put it all into one apk file.
Exactly. Android has a size limit on APK files, so we split it like that. Normally it’s solved with game downloading its own content but that requires CDN which can cost quite a bit, especially if people are deleting and redownloading game. Other games solve it by having people download content and manually put in specific folder, we don’t do that because if people fail to understand how to install with game just being split into 6 APKs explaining how to make folder and put files there correctly (which is also different between different phones) is much worse.