You need an MxID with an corporate email address. Do you have such one? Just send us a mail and we setup another account for you.
ALL, Please be aware that after signing up using the webpage, we will send you an invitation within a few days (much sooner in most cases). It is not the case that you can directly access sprintr.
I think the sprintr page is a bit overloaded. The first two times I got an strange error message. But I tried again to copy the message over here but suddenly I got an other page and now all is working. So just try again later I think.