Contabo

Contabo offers reliable and cost efficient virtual private servers.
Beside a wide variety of virtual private server sizes, and operating systems selection, they also offer VNC access, networking tools, backups and DDoS protection.

If all you need is to test drive Contabo, their smallest VPS offering will give you 2 VCPU and 4 GB RAM for just €3.99/month, but beware the storage is not fully SSD. Good news is their SSD offering start at €4.99/month and offer plenty VCPUs and RAM, depending on your needs.

Contabo's virtual private servers are unmanaged, of course, you could add a control panel, but that will increase the monthly pricing considerably but also the resources usage on the VPS.
When using unmanaged virtual private servers, you will need to install all the needed software by yourself and also manage the server during its lifetime.
In order for MailWizz to work on a VPS, it needs a web server, nginx or apache, it also needs PHP programming language, and MySQL or MariaDB to store your data. If you don't have enough experience installing the above or configuring a VPS, it is better you hire a system administrator to do all this for you.
When selecting a VPS size from Contabo to get started with MailWizz, we recommend using a VPS with at least 4 VCPU and 8GB RAM, VPS S SSD is a good choice to get started with Contabo and MailWizz.