Maybe try to spin up a new VM with FreePBX 14 and try to use the conversation tool
https://wiki.freepbx.org/display/PPS/Elastix+and+PBXinaFlash+to+FreePBX+Distro+Conversion+Tool
If it works, then follow the below instructions to move everything How to: Upgrade FreePBX13 to FreePBX14 on Hyper V - Guide