How do I combine software simulations?

Combine several software simulations in one project

Captivate 2019 character assets won’t download then crashes Captivate

I see there are often problems with downloading assets.  I am trying to access the characters with no luck.  It just says accessing assets and a waiting icon but does not do anything.  You cannot exit as it seems to have crashed each time I try. I am using release 11.5.5.553.  I have checked and this is the most up to date release. Can anyone help.  Very frustrating