A Routing Conundrum

I started to actually work on the authorization service (which I have decided to name Mabel) and quickly discovered to my shock and horror that silex/silex has been abandoned. Basically, this is the routing framework that I'm used to using and I wasn't expecting to have to change.

The suggested replacement is symfony/flex. To be honest I'm not exactly sure what symfony/flex even is. It guess it's some sort of code generator that allows you to create the skeleton of a Symfony project by executing a series of commands from the command line. I guess it also handles setting up the routing to your controllers the same way. I'm probably not doing it any justice in my 'description' but that was my takeaway from the documentation/marketing materials on the Symfony site.

It's a personal failing of mine that I'm too resistant to change. I'm deeply skeptical of any new technology until I get to a point where I feel like I understand whatever it's trying to be or do. Knowing that, I set my discomfort aside and decided to keep an open mind and try out this symfony/flex thing as potentially the new way forward.

Only I can't. I can't really install it. There's some sort of weird conflict happening because I'm attempting to use a combination of VirtualBox 6.1, Vagrant, PHP 7.4 and Symfony 5.

I'm not really sure what to do. Should I:

1. Switch to a different virtualization technology since this problem appears to be specific to VirtualBox?
2. Continue to use silex/silex even though it's been abandoned?
3. Find documentation that explains how to manually construct the routing in Symfony 5?
4. Find some other lightweight routing framework to use that I can install via composer?
5. Kludge together my own lightweight routing framework (possibly using candidates from 4 and silex/silex as an example)?

I'm really not sure which option to select. They all have their pros and cons.