Warning: Avoid random "cracked" or "repack" websites. Since 0.9.8.0 was officially free, there is no need to risk malware. Here are the trusted sources for the Space Engine 0.9.8.0 download:
Important Note: Version 0.9.8.0 is the last free public release. It is outdated, lacks modern features, contains bugs, and may not run well on Windows 10/11 or modern GPUs. For the latest version, purchase SpaceEngine on Steam.
Solution: Run Space Engine as Administrator, or move the entire installation folder out of Program Files.
Yes, absolutely. Vladimir Romanyuk (the developer) explicitly released all versions prior to 0.990 as freeware under a non-commercial license. You are free to download, share, and use them, provided you do not sell them or claim them as your own.
However, note that the developer requests that users who enjoy the program purchase the Steam version to support continued development. If you use 0.9.8.0 and love it, consider buying the modern version as a donation rather than a requirement.