To use OBS to stream to Accelevents simply select Accelevents as the Stream Provider and then select the RTMP option.
Setup your Session:
Go to Sessions & Speakers
Create a Session
On Session Details, Select Accelevents RTMP as Stream Provider
Copy the information available on the Streaming Key
On your OBS Account:
Click Settings > Stream
On the Service field, select the option Custom
Paste the Streaming Key to "Stream Key" field
Click OK to save your changes
Click Start Streaming to start your broadcast
If everything was done correctly, you should be able to view the OBS stream being displayed on your session in the virtual event hub.
Note: When testing your session, make sure that the event time and date is for right now so that you can view the live stream right now.