Access to both the API and to Apex REST Services is required for Groove to both read from and write to your Salesforce data. You can enable these on your Salesforce account either by user profile or permission set. Your Salesforce administrator controls your profile and its permissions.
Enable API/Apex REST Service access using Profiles
Click on Setup.
Go to Users and click Profiles.
Click Edit on the specific profile you're updating.
Scroll down and select System Permissions
Click Edit and then check the API Enabled and the Apex REST Services boxes
Click Save.
Enable API/Apex REST Services access using Permission Sets
Follow steps 1 - 6 from the previous section, but in step 2 select Permission Sets instead of Profiles as shown below