You’re mixing Spacebars syntax in with your HTML and injecting it into the template at run time. That’s not going to work. Just put pure HTML into the Spacebars.SafeString or move this all into the template itself, where the Spacebars syntax will get interpreted properly at build time.
I figured out how to do it and will write it here to help others. I was unable to find info about this in any of the docs:
var link = Router.routes['find_contact_persons_page'].path({companyId:this._id});
return new Spacebars.SafeString("<a href=\"" + link + "\"> Click Here</a>");