To log in, use this link or click the profile silhouette in the top right corner.
If you are a member, you can sign in using one of two different methods - using your Imperial login (thanks to Luc for setting this up), or using your Google account. All accounts created by signing in using the Imperial login will automatically be given edit rights - those using Google accounts will need to ask their team leads to give them access.
All non-imperial members will need to sign up using a Google account.