During the signup process you chose a Subdomain which became part of a unique website address where you will go to login.
For example, you may have selected SMITH as your subdomain. In that case your login address would be https://smith.crosstrax.co
Check the first email you received in which the subject line is WELCOME TO CROSStrax. That email contains your login information.
As another example below, I chose DEMO as my subdomain
Once you locate the page, bookmark it in your browser for easy access in the future.