The administrator of your company's UPTEAMIST account should provide you with the URL associated with your organization. Using that link, you will be able to access your environment at:
https://[your company's name].upteamist.com
For Office 365 Users
UPTEAMIST can connect to your enterprise's authentication system. If Microsoft Office 365 is in use, then you will be able to sign in to UPTEAMIST with the same username and password associated with your Office 365 account.