All Ehma’s music are under Free Art License. It means you can use whole of it as you want as long as you agree license.
It’s easy you just have to mention somewhere author’s name and the license (a link to license website is a good idea).
As mentionned on Free Art website :
[Name of the author, title, date of the work. When
applicable, names of authors of the common work and, if possible, where
to find the originals].
Copyleft: This is a free work, you can copy, distribute, and modify it under the terms of the Free Art License http://artlibre.org/licence/lal/en/
For example for this Website :
Works Ehma 1999-2019
Copyleft: These are a free works, you can copy, distribute, and modify under of the Free Art License terms http://artlibre.org/licence/lal/en/