Welcoming.
Welcome to Failed to download Boostrapper Fixes.
Download Synapse X(which has folders only and u need to add Synapse X.exe yourself).
This fix is not always necessary but okay.
Install a VPN (ProtonVPN) and active its free Trial
Then turn VPN on and run Synapse X.
This is a simple fix.
Check if any Anti-Viruses are not allowing Synapse X to run normally if you do have some i would recommend uninstalling them.
Or contact Bubble#1991 Or BORED#2278