Hi itsblacq,
the error says that your Standalone license is still active, and since the plugin license always go in combo with Standalone license, you cannot activate the plugin, until Standalone is still active.
Note that yoy can manially deactivate the license, by pressing the Sign-out button in the Account panel.
If you are not able to solve the issue, please send an email to
[email protected] with, sharing your Otoy user ID.
ciao beppe