It will help a lot if you have Google Chrome/some way to translate the page into English.
Oh goodness. Well. I went to this website and clicked on the leftmost download. I have no idea what the difference is. I do not speak nor do I read Japanese. When you get to the next page, the top section is for returning customers, scroll to the bottom and click the pink box under the red warning box. Enter your email address in the space provided, click the orange box, and there will be a confirmation link sent to that address. Go to your email and click on the link they send you to activate your account. Continue by entering a password (twice) a nickname, your gender, birth date, and “state of residence” (I just clicked a random one) and sign up for emails if you want, or uncheck all of those boxes if you don’t, and click the orange box to continue. Now your registration is complete and you can click the grey “next” box. This will bring you back to the Lovely song and again, click the left download box. The next page is terms and conditions with the “agree” box at the bottom right. Now all you have to do is type in your credit card information and it should bring you to the download page. I had a problem with one of my cards that I tried to enter and I know twentyonetrees had a few issues, too. I had to use my American Express credit card, as my Visa debit card was declined.
I hope this helps anyone trying to buy the song and if you have any more questions/if I didn’t explain anything clearly (I probably didn’t I’m sorry I’m trying) feel free to message me again!