When logging into the ReachDeck portal for the first time, you may see a 'Need admin approval' notification. This most commonly occurs when using a Microsoft email address.
You may have enabled 'require admin approval' for applications in your Azure Active directory.
By far the easiest way to grant permissions to an application is to have an Administrator visit ReachDeck.texthelp.com and sign-in with their admin users account. They will then see the following dialog which will allow them to grant consent on behalf of the organisation.
Alternatively the Administrator can control access to the ReachDeck App and grant permissions from within Azure Active Directory.