Hit a problem upgrading 3.5 to 5 (or 5.1)

I’m trying to do an upgrade from a USB 3.5. Followed the steps.

Fired up the download assistant. It came to a caution about 'Applications still active on this computer are using the eLicenser Control software" which I’m not as far as I know. Retry didn’t work so I had to cancel.
It finished installing the Download Assistant.
I logged on.
Entered the Access Code
It’s come back with a message “Application ‘LCC2’ has caused the following error”
"Process with the ID NOT found.
(then) Options: Click to abort.
.
Is anyone able to help with this, please? Many thanks if you can.

Edit: It’s jammed up my PC so I’ll have to end the task.