Kobo ereaders can't handle acsm files. In order to get Adobe DRM'd books onto your kobo you will need a PC with Adobe Digital Editions software on it. You'll need an Adobe ID (which you probably already have) and you'll have to use the ADE software to authorize your kobo.
Open the acsm files in ADE and the books will be downloaded to your computer. You can then transfer the books to your kobo.