The problem we ran into was that Springloops usernames are email addresses, and Coda only asks for your Git URL and password. This means your username needs to be included in the URL.
With a GitHub account, this isn't an issue - the URL will look something like https://github.com/yourusername/reponame.git
After some trial and error we determined that the trick with a username which is an email address is to URL encode it before inserting it into the repo URL.
Take note that with the Springloops URL the order is hostname, colon, URL encoded email address, rest of repo URL. For example:
Springloops Git URL: https://slsapp.com/git/yourspingloopsaccount/reponame.git
Coda URL: https://slsapp.com:youremail%40youremail.com/git/yourspingloopsaccount/reponame.git