The bitness version of the Total Access Emailer version you need is based on the bitness of your Access version, not the bitness of your Microsoft Windows operating system. Even if you are running a 64-bit edition of Windows, if the 32-bit edition of Microsoft Access 2013 is installed, you can only use the 32-bit edition of Total Access Emailer 2013.
Microsoft Office 2016, 2013 and 2010 do not allow the 32-bit and 64-bit editions of the same Office/Access version to be installed on the same machine.
The 64-bit Total Access Emailer setup program detects the bitness of your Access version, and installs the corresponding Total Access Emailer version automatically. If Microsoft Access isn't installed, you are prompted to choose which version to install.
The 32-bit Total Access Emailer program only installs the 32-bit version.