fcitx-table-dayi is a table input method for Da Yi. It's based on the Dayi3 and Dayi4 tables from OXIM project.
You need Fcitx main package to get it running.
There're so many of them on Taiwan local forums. (Google is your friend!)
Although they're all also freeware, permit everyone to use them without any responsiblity, and even input faster than or have less redundant mappings than these tables I chose, they themselves may potentially violated the original agreement from Dayi software corp (See COPYING.Data).
You can take this one as a skeleton, it provides functionality to use Dayi under Fcitx. You can still replace the .txt in tables folder to make a non- distributable fcitx-table-dayi yourself.
It's quite easy.
The table you downloaded might be in .cin format (Mostly).
You can simply rename it to .txt.
And delete everything except those between %chardef begin and %chardef end.
Then add a [Data] before them.
Add a header, see the current ones as examples.