There ARE alternatives, but. . . .
First of all let me just say that the easiest way is probably to just pay for the supported version.
However, if you for some reason WANT to expose yourself to hours of coding and testing, you can do as I just did.
I spent the last 3 days (yes, THREE days) making a bash script that reads the data from free fsacars serverlogbook.csv and converts the values from US to metric before it injects the data as a new pirep in the phpVMS database.
So it is possible, but not recommended, unless you really really really enjoy coding bash scripts 🤓