Programs get “installed on” a computer, not in one or to one.
However, you might also “install programs in” a particular directory.
You never install anything “to” anything else, though.
At greater length
Although text and data alike go ɪɴ files and files go ɪɴ
directories, directories go ᴏɴ filesystems just as filesystems go
ᴏɴ disk partitions.
When you consider other storage media like memory
cards or magtapes or floppies, you find again that files and directories
go ᴏɴ those things, but that cards go ɪɴ their slots just like floppies go
ɪɴ their drives.
Yet tapes usually do not go ɪɴ their drives (unless they get stuck and tangled there), but rather are
mounted ᴏɴ them the same way that one mounts partitions (well, filesystems) ᴏɴ directories.