Bitte! We're really happy you like our manga!
And yes, all of our manga can be downloaded as an ebook. The links for books 2&3 are in the main post, and here's the link for book 1.
Bitte! It's free on Pixiv, or you can get a downloadable ebook from Amazon here: https://www.amazon.com/dp/B08WR5X4LT/