The reason that the add-on will not start automatically is that the user does not have a valid SAP Business One license. SAP Business One dictates whether or not you can start up an add-on according to your license. If you do not have a license at all, then you cannot start an add-on.
However, SAP Business One has changed the way that licenses are assigned - there is now an indirect access user license.
The Add-On Access User is disappearing because SAP Business One is introducing the Indirect Access User, which offers users access to an SAP Business One add-on or SSP solution without requiring access to the core functionalities of SAP Business One. This is in alignment with the increased focus on the SAP Business One industry solutions approach and the growing demand of customers for SSP solutions and add-ons.
In addition, your customers now receive FIVE Indirect Access Users (named users) INSTEAD OF ONLY one Add-On Access User for the same price.
Please refer to SAP note 1270008 for more information about Indirect Access User Licenses versus Add-on Access User License.