@mrowand I just tried installing 1.5.10 on a fresh Rocky 8.9 VM. It went through and downloaded everything correctly.
Try running these commands on the server to see if you can manually download the files.
curl -kOL https://github.com/FOGProject/fos/releases/latest/download/bzImage
curl -kOL https://github.com/FOGProject/fos/releases/latest/download/bzImage32
curl -kOL https://github.com/FOGProject/fos/releases/latest/download/init.xz
curl -kOL https://github.com/FOGProject/fos/releases/latest/download/init_32.xz
curl -kOL https://github.com/FOGProject/fog-client/releases/download/0.13.0/FOGService.msi
curl -kOL https://github.com/FOGProject/fog-client/releases/download/0.13.0/SmartInstaller.exe
Let us know if this works.
Edit by Tom to ensure urls were accurate for fos files