Cloud based systems are usually virtual, and virtual systems are a no-go for real-time applications like Asterisk and Vicidial. Even the database will suffer from being virtualized in such a time sensitive environment. It's also unsupported by the Vicidial group.
That being said, most cloud providers can also provide dedicated hardware (for a higher price of course), and for testing purpose, a PV virtual machine setup is adequate, I just wouldn't bring that in prod. There's also stories out there of people getting it to work using some external USB timing device (Sold by Sangoma among others if you want to look into it), but again, I wouldn't put that in prod, if for no other reason than you'll have a hard time finding support for a VT Vicidial system.
If you want a hosted Vicidial, there's a lot of folks offering just that out there, and of course there's the Vicidial Group where you can get the good stuff right from the source.
*Edit*
I almost forgot: Welcome to the party!
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