Hi,
Should I first uninstall the 2008 version of Libronix Digital system when I install L4?
I have downloaded L4 but have received a prompting of not being able to log in.
You can run L3 and L4 together so no, you don't have to uninstall.
It would help to have a little more information. Have you actually installed Logos 4?
If so, remember that you must log in to Logos 4 using the email address and password that you use for your Logos.com account. You would not be able to log in if you did not use these.
Please let us know if you have installed Logos 4 and have tried to log in with your Logos email and password.