synology how many virtual machines can be run

Virtual Machines can only be run on models support VMM. Number of Vms that you can run depend on the VM workload , typically Number of CPU threads, and the memory requirement are 2 important variables to keep in mind while calculating the max number of Vms your machine can support. There is no single formula to calculate but the Free CPU power and Ram, Divided by the CPU power and ram of each VM gives you a fair idea