There are lots of spin bike on the market, but generally speaking they will not work directly with FulGaz.
To find out if your bike is compatible, make sure you have quit any other apps that can connect to your bike. Next, turn FulGaz on and see if your bike shows up in the list of "power" devices.
FulGaz should then speed up and slow down according to your effort.
Alternatively, you can go to Settings and put FulGaz in Steady mode. This will allow you to ride in front of FulGaz, but it will not speed up and slow down with your effort.
The only way a spin bike will fully work with FulGaz is if it sends power and receives resistance change commands via the bluetooth FTMS standard. We can then read this power output and control the speed of the rides accordingly. Using a speed or cadence sensor will not work because we have no way of knowing the resistance you are pedalling against.
Please understand that we don't have any spin bikes to test with, so we can't give you a firm answer on your particular bike.