I really recommend you to use VMware Fusion 11.5 as it is supported and doesn't have the security issues that VMware Fusion 8.5 has.
However if you really want to run VMware Fusion 8.5.10 on macOS Catalina, look at my answer here:
re. going from VM to bootcamp. There's no help page for that step AFAIK.
I appreciate your prompt help.
To be honest, the bells and whistles which both VMWare and Parallels offer are of little interest to me. I simply need to be able to run Windows for a few programs and then shut down Windows as soon as I can. I'd estimate 95+% of the time I use Mac OS. However, when I do use Windows, the advantage of having both Mac OS and Windows available is considerable, making bootcamp less attractive.
If someone offered a bare-bones method of running Windows, I'd bet there would be a huge shift to that bare-bones version assuming it was correspondingly cheaper.
Does bare-bones Windows emulation exist?
Virtualbox from our "friends" at Oracle is the only thing I can come up with nowadays.
It's free, so it is certainly cheaper, it is also pretty barebones I think.
I have NO idea if it runs on macOS Catalina, no intention to try it out myself either.
There's only two real solutions - Parallels and Fusion. Virtualbox is usually late to provide compatibility. Wine's even worse.
Fusion 8.5 is four years old. For the $49 upgrade cost, that's $12.50 a year, or about two starbucks.