Halion String Edition 2 won't open!

A few weeks ago I got Halion String Edition 2 software + elicenser - second hand.
When attempting to open Halion String Edition 2, I kept getting the same error message

“Application ‘Halion Player OEM 3.x’ has caused the following error
eLicenser(s) contain(s) no valid license for this application”

When I connected the eLicenser there was only one license - for Halion String Edition 2.x - on it.

I attempted to contact the person I purchased HSE2 from but unfortunately that line of enquiry is no longer possible or ‘appropriate’ due to ill health.

I was unable to find a Halion Player [OEM] 3.x license anywhere but I managed to buy Halion Player [Retail] 3.x software & license - thinking that would solve things.
The Halion Player [Retail] 3.x license is now on the eLicenser along with the Halion String Edition 2 license but the programme still won’t open and I’m still getting the same error message!
I also attempted to open Halion String Edition 2 with the addition of a Halion 4 license on a separate dongle but again - the same error message!
I can get Halion String Edition 2 to open using a Halion Symphonic Orchestra license (which includes Halion Player [OEM] 3.x) - but that seems a bit pointless!
Do I need a Halion Player [OEM] 3.x license to be able to open Halion String Edition 2?
Or should my Halion Player [Retail] 3.x license or Halion 4 license do the job?
And if I do need a Halion Player [OEM] 3.x license - where would I get one?
Any suggestions?
Thanks