What you see below the table are hints. The tooltip indicates how the pair of elements will be placed in the table relative to each other. The key with the arrow pointing to the left says that its first element will be located in the table directly to the left of the second. The key with an equal sign indicates that its elements can be in the table strictly in one column. But do not be afraid of it: the game itself gives these tips the right configuration. You just need to find a place for each of them.
After the download is complete, the downloaded file will be displayed in the notification shade (top), and will also be located in the "Download" folder (any file manager )
Install the downloaded APK file using any file manager or by clicking on it (on the downloaded file) in the notification shade
If you are installing apps for the first time not from Google Play (but using a file manager or browser), you will need to grant the appropriate permission. This is done only once.
If the file was downloaded with the bin extension, then there are 2 options:
Change the extension of the downloaded file to apk using any file manager ("rename" function)
To update the application, install the new version of the application over (without deleting) the old one.
This update will only be possible if the previous version of the application is downloaded from us. Otherwise, there will be a signature conflict and you will see the message "Application not installed".
For what "Signatures" are and what they are for, read here.