Is Free RDP Servers are Shared?

Yes, it is true and you`re using a shared hosting. There are many server hosting providers offer free server hosting.

Free hosting is not recommended for business website because it has limited features or resources. Also, most of the free hosting does not come under service level agreement thus they will not be liable for any downtime.

Also, you have to read their terms and conditions carefully because if you do not maintain backup copy and if they decide to shutdown free hosting service (which is possible), you may loss your data.

There is nothing wrong to use free hosting service for testing or learning purpose.